Mood Whiplash/Live-Action TV

Examples of in  include:

"Ken: What did I do to deserve this? Captain Joe: (pensive) We don't deserve half the things we get. (laughs maniacally, then throws down his pen angrily) You're stuck here!"
 * The outburst by Captain Joe in Fugitive Alien became a Memetic Mutation on Mystery Science Theater 3000.

"iHawk (despairingly): "This isn't a war...it's a murder." (* flips switch* ) iHawk (Groucho Marx voice): "Dis isn't a war, it's a moider!""
 * The Pilot episode of Lost has a good example of this trope. About mid-way through the two-hour series opener, the Losties get the radio from their plane working and hear a transmission in French. After a couple seconds of them cheering that the French are coming to rescue them, Shanon translates the transmission which says in part: "I'm alone, all alone the others are dead." The Mood Whiplash makes a creepy moment far more terrifying than it already would be, and this moment basically sets the tone for the entire series.
 * Possibly the most chilling moment in this show's history: in the season one finale, they're on the raft, they fire the flare--and suddenly there's a light! There's a boat! There's triumph music! They're saved! And then:
 * On a similar note, the soundtrack for this show. A prime example is "Life & Death": the first three minutes are a tearjerking meditation on well, life and death, and the last thirty seconds is you being dragged into hell.
 * Xena: Warrior Princess and The X-Files both tended to have goofy/stupid episodes in the middle of serious, depressing arcs.
 * Supernatural had goofy, self-referential episodes right in the middle of incredibly dark and bleak arcs. Season Two and Three are the guiltiest of this.
 * Forgetting certain episodes for a second, the basic premise and the actual tone jar together so much that it makes the show the western king of Mood Whiplash. Because, honestly, would you believe that a show that has the premise of two brothers hunting down demons with rock salt could be one of the most unbelievably downerish shows around?
 * Supernatural also had a case of internal Mood Whiplash in the episode "Mystery Spot." The episode starts out like a normal Groundhog Day Loop episode in which the same Tuesday plays over and over again, with only Sam experiencing the loop; the trigger for him to start the day again is Dean's violent and unpredictable death. Despite the dark subject matter, however, the first half of the episode plays like your standard goofy comedy installment - wacky montages, upbeat music, constant one-liners and jokes; until
 * Simon Said had this in spades. It starts with Sam having one of his painful death!visions, then Ash comes in for some comic relief and Dean sings REO Speedwagon, then Sam angsts some more and someone gets killed, then they find Andy's "Moby Dick Bong", then Dean gets mind-fucked (for the second time) into admitting he's scared for Sam and Sam has another death!vision, then Evil!Twin humor and then full-blown angst with Tracy's Mind Rape, seriously-painful-in-hindsight Foreshadowing of Dean's wish for death (he gets forced by Webber to put a gun to his head), more Sam!Angst and a not-so-nice twist in the "psychic-kids" storyline.
 * We can't forget episodes like Wishful Thinking, where we go from hilarity like a suicidal, alcoholic teddy bear and "KNEEL BEFORE TODD!" to Dean's confession that
 * Or Yellow Fever, where we start out with Dean running for his life from a tiny little yappy dog, and end
 * Or Changing Channels, with the boys trapped in Grey's Anatomy and a Japanese game show, ending with
 * Or basically any episode of the show ever. Oh Show, you're a manic-depressive but we love you anyway.
 * Scrubs features this rather prominently, being a comedy set in a hospital where people have a tendency to die occasionally.
 * The most egregious example must surely be: a pregnant couple find out that it is likely either the mother will die and their baby will live or vice versa, when the show suddenly cuts to J.D.'s fantasy before cutting back to dealing with the dilemma. Mood Whiplash so strong you'll be massaging your neck for hours.
 * And as a comedy set in war-torn Korea, M*A*S*H is even worse (or better, considering your point of view). You could be laughing hysterically one minute and within seconds, you could be left like you've just been punched in the gut.
 * This was parodied in Futurama; one episode had a robot surgeon clearly based on Alan Alda's character, which had an actual switch that it would flip to jump between jovial goofing around and war-weary angst (labelled Irreverent and Maudlin respectively).

"Buffy: When your blood pours, it might save the whole world. What do you think about that? Does it buy it all back? Are you redeemed? Andrew: No. Because... I killed him. Because I listened to Warren and I wanted to believe it was him, but I knew it wasn't. So I killed him, and now you're gonna kill me, and... this is what Jonathan felt. (he starts to cry)"
 * Joss Whedon does this All. The. Time:
 * Firefly has a tendency to quickly and unexpectedly shift from intense action to engaging drama to heart-wrenching sadness to laugh-out-loud hilarity to warm and fuzzy, within the space of a single episode.
 * The "He is psychotic!" scene in the pilot is particularly epic.
 * It's even got an example of a character getting the brunt of the whiplash. River is dancing, actually happy for once, while the others are having a wild west shootout, unbeknownst to her. Then Shepherd Book is wounded, and both the audience and River have the same reaction.
 * On Angel, the writers would frequently place an amusing or lighter-hearted episode before starting a dark story arc. More memorable episodes include the ballet episode that aired before the "Father will kill the Son" arc and the seriously amusing "Angel is a Puppet" which aired before the Fred/Illyria episode.
 * The start of the Fred/Illyria episode also qualifies. It starts off on a light note - Wesley and Fred are together, while Angel and Spike are arguing over whether cavemen or astronauts would win in a fight. Then Fred starts coughing up blood...
 * After the Darker and Edgier second season plot arc of "Darla and Angel", the creative team indulged in a whimsical 3-part season ender, set in a fairytale kingdom, to deliberately offset the grimness of preceding episodes.
 * And then at the end of that arc, Angel returns to earth and gets the news that Buffy died while he was away.
 * Let's not forget that this was also repeated in "You're Welcome", where after the day is won and everyone is celebrating, Cordy and Angel have one last kiss. She says, "You're welcome.", the phone rings, and Angel finds out she died that morning. Let the tears commence!
 * "Spin the Bottle" which is Angel's equivalent of Buffy's "Tabula Rasa" is a perfect example of this. The majority of the episode has the Angel Investigations crew all having their memories regressed to their teenage years and all sorts of wacky hijinx going on: Wesley returns to his wussy self from Buffy's third season, Fred is revealed to have been a pothead as a teenager, Angel's memories go back to before he even became a vampire and he mistakes a group of cars for demons... and then the end happens where everyone gets their memories restored.
 * Buffy is rife with examples. Oh, where to start... could it be with
 * The Puppet Show has one in-universe mentioned by Cordelia. In the talent show, her song about 'dignity, and human feeling, and personal... hygiene, or something like that' is set up to occur just after a band's rock song. She says something along the lines of, "The point is, my song is sappy, and no-one is going to feel sappy after all that rock and roll?" Giles quickly makes her go away by mentioning her hair.
 * Once More with Feeling contains an enormous one in addition to all the song-specific ones listed below. The episode begins with cheery singing and dancing and fabulous songs and end with the main character's attempting suicide! And then it end with a kiss...
 * Or "Tabula Rasa", with its 37 minutes of madcap memory-loss hilarity (including a kiss between Anya and Giles) followed by  Only episode of television that has EVER had me literally laughing one minute and crying the next. Very well done, though.
 * Or how about the zany madcap jaunt about a geek and his robot girlfriend that ends with  And then, of course, the geek turns out to be the bastard son of Lex Luthor and Max Cady.
 * Even without, "I Was Made to Love You" is still pretty whiplashy - like the part where April nearly kills Katrina after the latter "lies" about being Warren's current girlfriend, or when she "dies", still believing that Warren would come back to her.
 * Everything to do with the Geek Trio in Season Six has Whiplash. Just one example is in "Dead Things," when they start with a zany plan to acquire a sex slave then accidentally murder her and try to frame Buffy for it.
 * Storyteller is pretty much pure comedy... Then they get to the seal, and Buffy threatens to kill Andrew:

"Faith: Thank God we're hot chicks with superpowers."
 * "End of Days" has a serious dialogue where Buffy and Faith contemplate the loneliness of being a Slayer ending with the following line:

"Buffy: Did you just say something?"
 * Or how about "Standing", Giles' song from "Once More, With Feeling", in which he realizes that he must leave Buffy so she'll learn to stand on her own? He sings as he watches Buffy going through her exercises, and as the song ends, she walks up to him, unaware of what just happened, and:

"The Master: What do you think? 5.1?"
 * Or in Selfless where we go from Anya singing about how she'll be Xander's Missus, to her impaled upon Buffy's sword?
 * Episode placement will do it too...right in the middle of the 'Angel goes bad' arc we get a wacky story of Xander casting a love spell - then back to the pain and angst.
 * In the Season One finale, the Master is hamming it up during an earthquake. After the shaking stops, he turns to the Anoited One and asks:

"Mayor: [very deadpan] This officially commences the Hundred Days. Nothing can harm me, until the Ascension... [breaks into giggles] Gosh, I'm feeling chipper! Who's for a root beer!"
 * Or (told you Joss loved these), the whole ending scene of "Bad Girls", where the Mayor goes through the ritual to become invulnerable.

"Echo: Say, you got a bathroom?"
 * An unintentional example occurs in "The Body": the episode has no score, which adds to the harsh realism of an emotionally devastating story. Except nobody bothered to remove the loud, upbeat theme song from the end credits. It's somewhat jarring.
 * Another good example is the episode "Seeing Red" from season 6.
 * The Wish offers a good one - the alternate Sunnydale is ruled by vampires, the Master's still alive and kicking and now factory processing humans, and just about every main character dies. And then Giles undoes the wish and we're back to Cordelia, who'd died around the halfway point and was the one who made the wish, gleefully rattling off a series of wishes of what horrible fate should fall on Buffy, Xander, and Willow, and eventually all men while Buffy, Xander, and Willow cheerfully chat in the sunlight.
 * There's a pretty good moment that fits this trope well in the third season episode "Helpless." After learning that Giles is responsible for, Buffy directly confronts her mentor over his betrayal of her trust. The scene gets more and more dramatic as Buffy becomes more horrified and Giles tries to do anything he can to make it up to her, and then suddenly at the end Cordelia comes in completely oblivious as to what's going on. As Buffy coldy tells Giles, "I don't know you," Cordy takes her literally and believes some demon has given her amnesia, as well as wondering from their serious expressions if the world's supposed to end again and whether or not she should bother studying for an exam if that's the case.
 * Even Dollhouse has some:
 * In "Omega", Echo's line upon arriving at Alpha's lair:

"Darling: Made a note in my diary on the way here. Simply says..."bugger"."
 * Episode 2.11, Getting Closer: Topher and Bennett's, which leaves them both giddily happy; it manages to be both Crowning Moments of Heartwarming and Funny alike. Topher steps out for a minute and Claire walks in to have a conversation with Bennett that does nothing to lessen the charming atmosphere.
 * Ashes to Ashes has a lot of this. The season 1 finale in particular goes from farcical to heartwarming to OH SHIT in the space of about fifteen minutes.
 * The last 10 minutes of the Season 1 finale of Queer as Folk (US). Wow.
 * In a bizarre case where it's used for comedic effect, (and I may be wrong about the exact show, but I think I'm right) the old UK sketch show Not the Nine O'Clock News where two politicians are in a shouting match until one of them drops dead on the stage, resulting in a line to the effect of: "How can you believe these lies! This man... * URK* ...will be sadly missed, and our condolences to his family."
 * Doctor Who embraces this trope wholeheartedly whenever it would cause the Doctor the most angst. See "Journey's End", which has triumph, reunion and celebration followed by . The whiplash actually occurs in mid-scene, as
 * An example in the preceding episode "The Stolen Earth" is the beautiful reunion scene where the Doctor and Rose notice each other and start running into each other's arms when suddenly, out of the blue, a Dalek rolls up and shoots the Doctor.
 * It's not limited to the New Series, either. In The Green Death, after the menace has been destroyed, the Doctor's companion announces
 * The end of The End of Time:
 * A few of the regenerations could count as this, as we're basically witnessing a death and a birth at the exact same time. For this reason they typically take place right at the end or beginning of an episode/serial, as it means they can start fresh and avoid this trope. But other good examples of Whiplash would be Five's regeneration into Six (we go from his hallucinatory death scene right to Six snarking at Peri) and Nine's regeneration into Ten (his tearful goodbye to Rose right into a joke about having "new teeth").
 * "Doomsday" goes from a tearful farewell between Rose and the Doctor to the Doctor and Donna, wearing a bridal gown, shouting "What?!" at each other at increasing volume when she suddenly appears in the TARDIS.
 * The episode before, "Army of Ghosts," had a very large mood whiplash as well, with the Doctor being told by the Cybermen that "The Sphere is not ours."
 * Amy Pond goes through one herself in "Cold Blood" . It's disconcerting, to say the least.
 * "The Big Bang" does this so much, it'll leave your head spinning  It's hard work, this show is.
 * Also, in "Partners in Crime", when Donna and the Doctor are both chasing the head of Adipose and her hostage. Donna is watching through the door window, and the Doctor is watching through the window in the wall across from the door. There's a very serious questioning going on. Then the Doctor and Donna catch sight of each other. Hilarity Ensues. Then, mid-word, Donna realizes that they've been noticed. Cue chase scene.
 * "The Doctor's Wife" cuts from
 * Despite being somewhat dark, "The Almost People" wraps things up on a fairly hopeful note...
 * "A Good Man Goes to War", the mid-series finale, ends with (among other things) everyone finally learning just who River is. Cut to a card telling us the Doctor will return in Autumn with "LET'S KILL HITLER."
 * In "The God Complex" not only do the viewers experience it at every turn but so do the characters when they are possessed.
 * Torchwood is not without its own Mood Whiplash. The most blatant comes from the season of Torchwood: Miracle Day, where a scene goes from nostalgic-romatic, to comedy, to angst, all in the same scene and within the space of a few minutes.
 * Tonight, on a very special episode of Popular, Harrison must resolve his mixed feelings about his mother when his friends discover that she's gay...
 * ...and Mary Cherry chains Gwyneth Paltrow's personal shopper to a pipe in the school boiler room.
 * Rescue Me thrives on this trope. One minute you'll be rolling on the floor at the various antics of the guys of 62 Truck, two seconds later a bunch of kids die horribly in a fire. Pretty much every episode is like that.
 * The Burn Notice Season Four episode "Friends and Enemies" is mostly lighthearted at first, with the week's client (a spy that Mike accidentally burned) being introduced to the trio's dynamic and making lighthearted banter. The villain is even defeated by having the police catch him with guns in his trunk--a trunk that snaps open dramatically two moments, after the car flips, spilling the guns all over the street.
 * Battlestar Galactica - "Sometimes a Great Notion": after discovering Duala cheerfully reconciles with her estranged husband
 * Thanks to the ensuing commercial break, the mood whiplashes again so suddenly you half expect your spine to break from it. The commercial itself starts at 1:58
 * Blackadder - The finale of the fourth series suddenly takes an abrupt swerve out of comedy territory in the final five minutes. The entire final episode features Blackadder once again attempting to get out of "The Big Push", that is, everyone in the trenches entering No-Man's Land assaulting the German front. In previous episodes, he and the other characters have gotten out of these assaults, but at the end of this episode  There are no jokes in these last few minutes whatsoever, it's entirely dramatic, and in a comedy series, this comes as being a very unexpected Tear Jerker.
 * A specific example of a beautifully-executed mid-sentence Mood Whiplash in this episode comes when Captain Darling,  is listing all the things he'd hoped to do when the war ended. "Go back to work at Pratt and Sons" gets an audience laugh, as does "Keeep wicket for the Croyden gentlemen", but these are followed by a brief pause and a wistful "Marry Doris". A character who'd been portrayed as just a petty comic foil to Blackadder up to that point suddenly gets humanised.

"George: Well really this is brave and splendid and noble...[pause]...sir? Blackadder: Yes, lieutenant? George: I'm scared, sir."
 * George gets a very similar mid-sentence whiplash.

"Darling: Listen - our guns have stopped. George: You don't think... Baldrick: Maybe the war's over. Maybe it's peace! You actually start to feel hopeful for the characters that fate has intervened and they have escaped certain death, and then Darling says... Darling: Thank God! We lived through it! The Great War, 1914 to 1917! ...And we know that the First World War actually ended in 1918."
 * There are jokes right up until Blackadder's penultimate line, but they are all extremely grim. It's called Trench Humour for a reason.
 * And of course that moment moments before the end where they are lined up ready to go over the top, artillery booming in the background, when... silence falls.

"Holmes:"
 * That Mitchell and Webb Look referenced the famous Blackadder example above in the fourth series's penultimate episode, joking that they would follow suit and see the show off dramatically. Fast forward to the last sketch of the series a week later, in which Dr. Watson visits a dementia-riddled Sherlock Holmes and through a very silly exchange allows him to think he's still the cleverest mind in England.

"Malachai: You don't understand... O'Neill: I lost my son!"
 * The Hogan's Heroes episode "Operation Briefcase" was surprisingly dark, featuring an agent actually dying (offscreen) while in Hogan's care, when most involved escapes by the skins of their teeth. Even more unpleasantly, this episode dealt with an attempt to assassinate Hitler--an attempt, as everyone should know, that failed.
 * In the Batman Cold Open of another episode, the guys are meeting an Underground agent who was a female impersonator before the war. Jokes fly, then Germans crash the meeting, fire at the good guys and take off in pursuit of the Underground agent. Hogan and his men get up again, Newkirk cracks a joke at the expense of the French... and they realise that LeBeau is still on the ground and has actually been shot. Cue one of the most dramatic moments in the (usually) comedic series when Newkirk does a 180 from his usual Deadpan Snarker persona and says quietly, "Colonel, my little mate's been hit."
 * Stargate SG-1's most prominent comedy episode "Window of Opportunity" ends with one of these. The episode's all wacky time-loop fun until we find out why the archeologist is looping time; he's trying to bring his dead wife back to life, which of course leads to an outburst from the usually jovial O'Neill:

"Harry: (speaking to God) You remember that one guy? Of course you do, you remember everything. I tell ya, that one shook my faith to the CORE. Then you drop this brand new life, right into my hands... But if I could just have the answers to a couple of questions, like if you've always been here than where did you come from? And does man have the capacity to rid himself of his own evil? And why IS the sky blue anyway? Well, maybe I can look that one up. But all this baby stuff... that's no accident, after all you gave us Mozart, Van Gogh, Confucius, and LARRY BIRD!" * pulls a basketball from under his robes and tosses it through a hoop nailed on the cross*"
 * The end of the Stargate Universe episode "Light". The mood the entire episode has been one of resignation. Then Rush realizes that they're all going to live, and the mood shifts to elation. Then they realize that Destiny is accelerating too fast for the shuttle to catch them, and the mood shifts again to action, as the crew work together to get the shuttle back home.
 * Power Rangers RPM. Jesus. For a season that has unquestionably the darkest plot Power Rangers has ever done, this series also seems to have some of the most off-the-wall humour. Highlights include Ranger Green attempting to use his teleportation ability, only to teleport his suit, leaving him in his helmet and underwear, Ranger Green getting a wedgie from a disembodied robot hand, Ranger Green fumbling his one liners, Ranger Green... y'know what? I think you get the idea.
 * Likewise with Dr K. At first she just seems a little strange and kinda funny, being protective about the ranger tech and even wearing bunny slippers in one episode. Though all urges to laugh at her behaviour suddenly go away when you think of her back story...
 * On Deep Space 9, "The Magnificent Ferengi" bounced back and forth between ridiculous and awesome repeatedly. Especially evident in the end, when Quark's team has just beaten the remaining Jem'hadar in a shoot-out and captured their Vorta leader, the triumphant mood is suddenly turned hilarious by showing the dead Vorta (reanimated with carefully-controlled electrical impulses) trying to walk into a wall, with Nog saying "I can't turn him off!"
 * Night Court did this from time to time, often going all the way around back to funny in the same scene. In "Leon, We Hadly Knew Ye" Judge Harry's foster son (and recurring character) Leon successfully runs away when he can't stand his nice, but prudish new adoptive parents. He's not seen again for the rest of the season. "The Hurricane: part 2" goes all the way back around to funny again. After helping deliver the babies of four couples during a thunderstorm and blackouts Harry slips away to have a deep and emotional talk with God in front of a cross someone left in the courtroom.

"Angela: I mean, is this about Vincent? Brennan: ...Yes. Angela: Yeah. [Angela starts to leave] Brennan: And... I got into bed with Booth last night.] Why aren't you saying anything? Angela: Because I don't want to yell "Hallelujah" so close to losing Vincent."
 * Dead Like Me lives and breathes this trope... Ahem.
 * Sesame Street, when dealing with the death of Mister Hooper. The scene where Big Bird shows his drawings of his friends to the adults is light and cute ... up until the point where Big Bird says he wants to show Mr. Hooper the drawing he made of him. The mood then turns changes abruptly as the adults have to explain to Big Bird that Mr. Hooper has died and he won't be coming back.
 * Tokusou Sentai Dekaranger had one episode where the Blue Ranger had to kill his girlfriend's little brother because he was killing women to cure his sister's fatal disease... Which she was already getting better from in the first place. The scene ends with him watching his girl cry over her brother (in a rubber monster costume) in the rain with this sad whistling song... And then you get a neck sprain from the series' usual jazzy nightclub-ish end theme.
 * Band of Brothers did this with episode to episode continuity. The last two episodes go from finding a Nazi concentration camp to them going into Hitler's summer home and hilariously looting it of everything of value (up to and including the photo album of his summer vacations).
 * Common in Pushing Daisies, as it takes place in an extremely bright, beautiful universe and has some hilarious dialogue, but all the main characters have pasts that vary from the merely sad to the downright traumatic.
 * The "Polar Special" on Top Gear, in which the three presenters attempt to reach the North Pole, two by truck and one with a dogsled, is out of tone with the light and rather silly stunts the gang usually pulls, sometimes jarringly. The danger involved and the fear and discomfort of the presenters is simply too real to be played for humor.
 * Also the episode where they paint their cars with messages as offensive to Southern Americans as possible (pro-gay, anti-Nascar, etc.) and try to drive through Alabama without getting murdered by those wacky rednecks. It's all played for laughs until they hit New Orleans and see the devastation caused by Hurricane Katrina.
 * That entire thing is whiplash after whiplash. First it's funny, then it gets really creepy considering those rednecks were probably very serious, followed by the very serious "we shouldn't make jokes around here" air in New Orleans. Followed by a Crowning Moment of Heartwarming by giving away their cars (as opposed to selling them for a bit of a laugh).
 * Right after Tom Cruise and Cameron Diaz, James May segues (complete with lampshading of the mood change) into a 15 minute piece on Ayrton Senna, who would have turned 50 that year.
 * The BBC Adaptation of Cranford can be quite frankly emotionally exhausting to watch. Funny and witty one moment, heart-breaking the next. Then melancholy. Then heart-warming. Then...you get the picture.
 * The ABC series Hungry Beast swaps between sketches and serious current affairs, so in one episode you may have an exposé on the continuing problems of asbestos in Australia and a hilarious competition between Australian broadband and a pigeon in the same episode.
 * Being Human (UK) constantly whips between wacky sitcom hijinks and extremely gory supernatural horror, which can be more than a little jarring.
 * Sports Night did this too many times to list.
 * News Radio tried this with the episode dedicated to Phil Hartman's death by inserting jokes to lighten the mood. It didn't work too well; the real-life tears from the cast were too overwhelming for much of the episode to be really funny.
 * One episode of Bones ends with Brennan singing "Girls Just Wanna Have Fun" in a bar. Everyone's having fun until
 * In "Two Bodies In the Lab", Booth insists on staying with Brennan in her apartment after someone shot at her. At one point he notices a Foreigner CD in her music collection, and Booth and Brennan start rocking out to "Hot Blooded". Shortly after, Booth offers to get Brennan a beer. Just as he opens the refrigerator, he ends up getting the brunt of an explosion from a booby-trapped door.
 * The trope is also invoked in the episode "The Hole in the Heart", in this conversation between Brennan and Angela:

"Spencer: She used to say "Winder" instead of "Window". (Everyone laughs) Spencer: She's dead now. (Silence) Spencer: She fell out a winder! (Everyone laughs) Spencer: No, I'm kidding, she had a heart attack."
 * In the final episode of season two of Robin Hood Marian was . The first episode of season three dealt the raw and bloody emotional aftermath of this. But the next episode involves Robin laughing his head off as he hang-glides from the parapets of Nottingham Castle, and Marian was only mentioned a handful of times throughout the rest of the season.
 * Farscape manages to do this so-often that you would swear the entire show was bipolar. Prime example, in the episode "Revenging Angel" where John gets knocked unconscious due to a comedic accident... cue Harvey appearing in his coma-hallucination telling him that he's dying... cue John turning his entire reality into a Looney Tunes world... cue slap-stick and John asking all the main characters in his head how he should survive... cue his entire world blowing up and him flatlining. This is a one-episode example. Often the show will jump from the serious arc plotline with horrific and damaging psychological implications for the characters to good old harmless space opera fun in a very short amount of time. Admittedly the show is made of Crazy Awesome but there is a heavy emphasis on the crazy.
 * Skins did this one in series 4; sandwiched between Freddie's Episode 5 (which ends with ) and Effy's Episode 7 (which ends with ), is JJ's episode, which is an almost too saccharine love story (in which ). It sticks out like a sore thumb, doesn't advance most of the other arcs of the series, and is suspected by some to exist primarily because of Executive Meddling.
 * Babylon 5 has a lot this. J. Michael Straczynski has gone on record saying something to the effect of "I just love giving viewers a nice, happy scene, and them slamming them on the back of the head with a 2x4." He especially liked doing this as the introduction to a Wham! Episode; making the episode look like a light walk in the park, then suddenly flinging you into the Myth Arc at breakneck speed.
 * True Life has this, an episode about drug use may be followed by an episode about summer flings.
 * In the Star Trek: The Original Series episode "The Ultimate Computer", a malfunctioning computer controlling the Enterprise manages to kill several hundred crewmen aboard the other Federation ships engaging it in a mock exercise. No more than a minute of screen-time after the situation is resolved, Kirk struts back to his captain's chair and plops down with a massive grin on his face and a traditional "Everybody Laughs" Ending - accompanied by silly music.
 * The Star Trek: Voyager episode "Infinite Regress", where Seven of Nine starts manifesting the personalities of people she assimilated. So in the middle of her descent into madness we get a comedy scene where she's a Ferengi trader. And then we immediately switch to pathos as she becomes the confused mother of a Starfleet officer, who was supposed to meet him at Wolf 359 (site of the big battle in "Best of Both Worlds"). And then the Fridge Horror creeps in on a sweet early scene of her as a little girl playing with Naomi Wildman, when we're reminded that this little girl was assimilated.
 * Another one involving Seven of Nine manifesting other characters was when the Doctor's program is downloaded into her nanoprobes. Initially this is played for comedy, with Jeri Ryan doing a hilarous pastiche of the Doctor's pompous mannerisms. And then it suddenly turns dark when Seven learns what's happening, and she feels violated.
 * How I Met Your Mother had the episode "Bad News" which pretty much played out as a standard infertility story where Marshall and Lilly go to a feritlity specialist to get test to see why they are having problems conceiving (we already know Lilly will get pregnant). The usual Hilarity Ensues with Marshal being locked in a bathroom having to get a sperm sample while his mother is talking to him through the door (unaware of what is going on). Robin has some bad first days at her new job where she becomes the new Butt Monkey. By the end everything seems to have worked out, Marshall and Lilly are perfectly healthy, Robin has managed to turn things around at work and we think that the episode title is just a spoof. Then at the very last minute . Marshall's reaction is a complete Tear Jerker.
 * Keeping Up Appearances has fun with this trope. Hyacinth shops for a second car; A crime thriller ensues. Hyacinth tries to help her sister fix her marriage; An epic foot chase ensues. Hyacinth goads Richard into repairing some electrics and babysits dogs; The dogs run away when the church is turned into a virtual war zone and explodes.
 * Tomica Hero Rescue Fire had an extreme example of this in one of the final episodes. Joukaen, an Axe Crazy fire-demon learns that humans are not the corrupt lifeform he thought them to be. Therefore he confronts his lord, Donkaen, only to learn that Donkaen turned him against the humans in the first place. So in a last effort to make up for this, he fights Donkaen and gets killed. One second after his death, the credits roll, with a very upbeat song as background music.
 * Used to chillingly good effect in the episode Queen of Hearts in Merlin. King Uther initially thinks it's hilarious that Arthur has been caught making out with Guinevere in the woods ("I was young once, I know about the temptations of serving girls!") only for him to coldly banish Gwen from Camelot on pain of death once Arthur declares his love for her less than thirty seconds later.
 * The episode also opens on a note of Mood Whiplash in which Guinevere's beautiful sunlit coronation is suddenly interrupted by Morgana waking up in a panic, the whole thing having been her prophetic nightmare.
 * Season four premiere has Arthur, Merlin and the knights wandering in a desolate village. Tension is mounting and they don't even know what kind of monster they are looking for. Suddenly, Gwaine takes a bite from an apple, startling everyone and breaking the tension. Only for Elyan to discover dead bodies.
 * The Doctor Oz Show tends to do this in episodes with serious topics. It may start off with somber conversations with women who have lost family members to cancer...and one tiny commercial break later, audience members are passing brightly colored balls representing poop through a plastic tube representing the colon, with everyone laughing and cheering at a successful "bowel movement" into a plastic bucket.
 * Game of Thrones features a lighthearted scene about Arya catching a pigeon and trying to trade it for a pie,
 * In the same episode, a humorous scene in which Tyrion, Bronn, and Shae play a drinking game leads into the tragic story of
 * Scream Queens acknowledges this very trope in its second series when John Homa is teaching the girls how to cry in scenes. One girl is told to laugh hysterically about stories she's telling at Christmas, when Homa suddenly tells her to imagine that the stories are about people who aren't alive anymore.
 * Done many, many times in Frasier, when a scene that is initially Played for Laughs becomes, upon further elaboration, much darker or more emotional than before. For example, Niles discovers that his wife Maris is cheating on him with his marriage counselor through a hilarious scene of Missed Him by That Much where both he and the counselor think they are preparing for a steamy night with Maris. This leads to an equally hilarious confrontation, and an even more hilarious scene where Niles' anger at his wife boils over while coaching a group therapy session; only for the scene to turn into a Tear Jerker halfway through when he bursts into tears and starts screaming at an absent Maris that he has never, ever cheated on her despite being tempted by Daphne, who treats him well and is a far better person than Maris is, for years, and finally breaking down sobbing that "I wanted to believe that [Maris has been always faithful to him] more than anything in the world, but now...now...I just can't see how I can...Now I just want to die."
 * Oh God, Daphne when Niles is having heart surgery. It's terrific writing and acting because the others make the jokes and act as you would expect but Daphne is sat wondering if she is going to lose Niles not that long after they have finally finally managed to get together. Almost as good is the terrific scene with Martin who is equal parts reproachful, compassionate and understanding with her when he says "It's hard as hell for all of us".
 * NCIS does this in the episode "Two-Faced" (8.20). In many episodes, the final minutes after the climax are dedicated to comedy or romantic drama, and this is what it looks like when Tony and Ziva are sitting at a bar talking about their relationships (with a colleague and a liaison CIA agent respectively) when suddenly, the music changes and then... eyeball in the icecube. And their expressions: FUCK.
 * Kate's  at the end of Season 2 too.
 * The Six Million Dollar Man: Due to a decision not to air the tragic original The Bionic Woman two-parter at the end of the season (even though it was filmed as such), viewers saw Steve grieving for Jaime one week, and then his usually happy-go-lucky, womanizing self the next week.
 * Community has an episode where the guys are listening to a Video Will Pierce's mom left behind on a CD. The first track on Pierce's mother's CD is a recording of her pleading with him to understand the finality of death. The second track is hardcore gangsta rap.
 * The later seasons of Boy Meets World had a lot of this because during those seasons the show had a lot more serious plotlines while continuing to be a sitcom, so in the more serious episodes comedy relief scenes were injected between the serious scenes. A lot of the episode had a Two Lines, No Waiting setup where one plot was comedic and one was serious.
 * West Wing Has one of these, completely unintentionally. Season 1 ends with someone opening fire on the president and crowd and as the visual fades you hear "Who's been hit? Who's been hit?" and then...there's the exceedingly peppy end credits music.
 * The show often does intentional versions of this trope too. The most extreme is probably "Take This Sabbath Day," where the episode alternates between the gut-wrenching, extremely dark A-plot of Bartlet debating whether or not to commute the sentence of a man on death row scheduled to be executed by midnight, and the side-splittingly hilarious B-plot of an extremely hungover Josh experiencing Disaster Dominoes while bickering with a congressional campaign manager.
 * Done deliberately as part of the format in Doc Martin, every episode will contain one dark, serious and weighty storyline, and one light Quirky Town style story. They will then interleave throughout the episode, often with both story lines crossing through the same scene, and leaving the viewer pretty wrung out emotionally by the end.
 * An In-Universe example from iCarly:


 * The third season Modern Family episode "Virgin Territory" goes from a serious discussion and realization of girls growing up quickly to scenes where Luke and Manny, both too young to drive, try to impress a girl by slowly driving Mitch's car.
 * Friends occasionally does this, and never more than in the episode "The One With the Morning After" which deals with the fall out of Ross sleeping with another woman behind Rachel's back after believing she's left him. Even though it's a fairly serious episode, the majority of it still has a few hilarious moments such as Ross and Rachel taking a brief break from their fight to order pizza and Rachel intentionally ordering anchovies mixed in with the toppings and sauce because she knows Ross hates them. However, the very last scene completely abandons the humorous aspect and goes completely serious. Even the brief moment where we see the remaining four other characters still trapped in Monica's back room is suddenly much more serious as they're all somberly listening in to the conversation, with Monica and Phoebe even breaking down into tears as they all realize that their two friends' relationship is over.
 * A Taxi episode had Jim buying an over-the-hill old racehorse and keeping it in his apartment. Typical Jim hijinks, but the horse inevitably dies. Jim gives it a funeral, and gives a truly sweet, moving eulogy that chokes up the rest of the cast (and plenty of viewers.)
 * Done rather tastelessly in an episode of America's Most Wanted. In the re-enactment, a desperate fugitive looking for shelter runs into an unlocked house to find two rednecks. They chase him out with baseball bats while banjo music plays and John Walsh wryly notes "They weren't in the mood for company." Then the next unlocked house he goes to has an old lady who he brutally murders.