Ping-Pong Naivete

"Stewie: No, no, it's... it's nothing, just had Play-Doh spaghetti last night (pauses) (under breath, looking away) and that's all we had last night...

Olivia: (angry) What does that mean?

Stewie: Oh, I don't know, Olivia, uh... maybe that we are in a sexless marriage? We have yet to have sex.

Olivia: Do you even know what sex is?

Stewie: (angry) That's not the point! Don't change the... it's a kind of cake?"

- Family Guy

A character who, due to previous experiences, should know better but doesn't. But later, he displays that he does. But then he doesn't, and so on, and so forth.

This is extensively used either for quick, cheap momentary jokes and gags, or to hold the plot of the particular episode together. It also helps maintain the status quo. Expect to find it in a series with inconsistent character development and Negative Continuity.

Compare Idiot Ball, Smart Ball, and Aesop Amnesia. See also Depending on the Writer. Usually justified by Rule of Funny. Can be considered a subtrope of Cloudcuckoolander.

Anime and Manga

 * Misa Amane in Death Note. Occasionally competent enough to pull off a good Plan, usually a Genius Ditz. Blame the Mad Love.
 * Nao Kanzaki from Liar Game, to an annoying extent. While at first she was thrown into a world of lies and tricks, despite being "honest," she doesn't seem to understand the point of the Liar Game. First tricked into giving 100 million yen to a "trustworthy" teacher, then almost screwed Chessmaster Akiyama's plan by making a part of the team the most unreliable person, Mr. X, in the round and then trusting said unreliable person, after she had learned of Mr. X's true nature. Between her mistakes, she shows some bits of understanding her situation, but she forgets them when it's important. If it weren't for Akiyama, she'd be screwed by now.
 * In the drama series this is very much true. However, in the manga series it becomes less as time passes. In the current round, she managed to . Also, when the team threatens to fall apart she convinces everyone to keep working together.
 * Putting Mr. X part of their team wasn't exactly her fault, since at that time, they didn't know who Mr. X was. And as noted above, it happens much less later on in the manga, With Nao actually pulling off some of her own tricks.
 * Currently, she pissed off Yokoya by telling him that he's such a wimp since he cannot stick with his own philosophy of being "dominator". AND that after he cornered Akiyama's idealism by telling him that he can't stick with idealism of making LGT the enemy.
 * Atsushi Arisawa from Kusatta Kyoushino Houteishiki is a Genius Ditz who consistently gets some of the best grades in the country, was invited to an elite highschool in Tokyo without an entrance exam and who sometimes has enough insight on other people's relationships to identify core problems and underlying psychologies that no one else sees. Unfortunately he has no idea that he's actually that smart, goes to a highschool for delinquents, doesn't see why he was invited to an elite highschool in the first place, completely misses the most obvious aspects of most people's relationships, and has the surface mentality and naivety of a small child on a sugar high! Yes, this is very frustrating!
 * Sakura Kinomoto, who manages to capture Clow Cards using her brain and ingenuity but remain oblivious about people's affection to her.

Comic Books

 * The eponymous character of Street Angel is a 12-year-old, homeless, alcoholic Heroic Sociopath who at one point mistakes a Double Entendre for a euphemism for cannibalism.
 * Max from Sam and Max. At times, he's making lewd sexual come-ons and innuendo about sadomasochism, masturbation and drug use; at other times, he's a childlike Chaste Hero who doesn't even understand the biological differences between men and women. It's lampshaded in his Image Song in the Telltale games, which flat-out calls him "a sandwich of naivety and cynicism."

Literature

 * Besides his famous Sherlock Holmes stories, Arthur Conan Doyle wrote a series of humorous adventure stories about Large Ham Napoleonic soldier Brigadier Gerard. While in some stories, Gerard is rather clever and appears competent despite his inflated opinion of himself. On the other hand, he is a dolt in others and very much an Unreliable Narrator.
 * Bertie Wooster constantly wavers between "mildly ditzy" and "hopelessly idiotic," the guiding rule seeming to be "whatever is funniest in the current situation." For instance, he'll briefly become Literal Minded, despite the fact that he frequently uses analogies and common expressions himself.

Live Action TV
"Summer: Kidding, I'm not stupid, just shallow."
 * Vala Mal Doran's knowledge of popular culture in Stargate SG-1 is inconsistent in the first few episodes of season 10.
 * Summer Roberts from The OC swings wildly back and forth between being a clueless, uniformed airhead and a savvy student who aced her SAT scores and got into Brown.


 * The 'bots on Mystery Science Theater 3000 do this on purpose to mess with Joel and Mike.
 * Adrian Monk is, for example, still convinced that his college roommate's girlfriend was helping him organize whenever there was a tie on the door, or similar things whenever it's funny, but always becomes an expert on human behavior just in time for The Summation.

This may partly be an example of The Cobbler's Children Have No Shoes, as with the case he's dealing with, he's usually outside of the problem.
 * In 3rd Rock from the Sun, the aliens' knowledge of Earth. One particular example is a second-season episode in which it's mentioned that Sally is going bowling. A fourth-season episode had her going bowling for the first time and not even knowing what it was. For the first two seasons, the Solomons were terrified of Jell-O (thinking it was a dangerous alien entity) yet in a first-season episode Sally mentions making "Jell-O with cheese." Dick is sometimes supremely sarcastic, but at other times he doesn't seem to be able to recognize sarcasm and interprets everything literally.
 * A particularly severe example is the episode when, very late in the show's run, and after hundreds of scenes in restaurants, the aliens finally figure out what "tipping" is.
 * This is worked into the plot, however, as Mary is horrified to find out that Dick hasn't been tipping the waiters when they've been going out. Suddenly all the rudeness on their return visits makes sense to her.
 * Happens all the time on House, with characters who have known the eponymous jerkass doctor for years expressing varying levels of shock every time he does something insane or unethical, to the point that the one time somebody reacted some other way instead, it was a symptom of a . These same characters, however, will at other times act familiar with his behavior patterns, usually for a gag. All of the above also applies to his rudeness toward patients and tendency to pull the correct diagnosis seemingly out of nowhere just when things look bleakest.
 * And it even happens to House himself. He's deeply cynical about the state of things most of the time but when it comes to dealing with a hostage-taker with a gun, Vogler, Tritter, Stacy and sometimes problems with Wilson and Cuddy, he's naive and mainly likes to keep his head stuck in denial-land.
 * Played for laughs, a lot, with Liz Lemon on 30 Rock. She's the head writer for a comedy show that mocks pop culture in one scene, and then she'll pull out archaic slang like "discotheque" un-ironically in the next.
 * Nearly everybody on Heroes displays this at some point. Peter and Mohinder are the most frequent, but even general BadAsses like Noah Bennet and Sylar have conveniently forgotten things they learned or should have figured out several episodes earlier.
 * In another alien example: Mork. One moment he mentions he still doesn't know where babies come from, the next he's making subtle sexual innuendos. This is probably the result of Robin Williams sticking to the script half the time and Getting Crap Past the Radar for the other half. It got particularly bad in the second season when ABC wanted Mork to become more "hip".
 * Bones demonstrates this perfectly. She is baffled by standard cultural references that everybody else (Booth, Cam, etc) understands while constantly not understanding human motivations, yet she is a best selling author with believable characters in her books who supposedly comprehend those same cultural references and have those same motivations that she doesn't understand in her real life.
 * New revelations reveal a new explanation in this instance..
 * It's not that she doesn't understand human motivations, it's that she lacks the understanding of the logic behind it. For example, she understands that Booth believes in God, yet does not see why he does. You can write something without agreeing or understanding it. Ask any high school student.
 * It also helps that many of her characters are based on people around her, making it a simple copy/paste sort of thing.
 * Used to a frequently irritating degree for cheap jokes on NCIS, usually at the expense of either Tony or McGee. Gibbs knows about technology(or doesn't), Ziva understands idioms and pop culture (or doesn't) . . . etc.
 * The Doctor, as a character trait. Even the Tenth Doctor, considerably more sexually/romantically inclined than most of them, had moments of being Oblivious to Love (sharing the bed with Martha in "The Shakespeare Code," being offered a phone number in "Partners in Crime").
 * His naivity to Earth pop-culture in general, as well. In his earlier incarnations, he was definitely a Fish Out of Water, so that's fine. But now he's on his Eleventh incarnation, fanboys over famous human artists, and has made references to everything from Ghostbusters to The Lion King. Which makes you wonder how he forgot what football/soccer was.
 * In particular given he seemed to mistake it for cricket, which he has played before quite well and displayed a knowledge of in his fifth incarnation.
 * Perhaps justified in that, especially by his Eleventh incarnation, the Doctor has a fantastic quantity of knowledge about the universe and just like is often the case with even normal humans, the more you know in general the harder it is to at least immediately recall specific pieces of information.
 * The titular character from Sherlock. In one episode he's so oblivious John has to explain to him what a date is, while in another he is able to successfully manipulate another character by appealing to her romantic feelings for him. And then in another episode he correctly deduces that this same character is in love with someone, but is very surprised to find out that it's him.
 * It's heavily implied that he's being deliberately obtuse about the date in question. And understanding sexual attraction is a bit different than understanding unrequited affection.

Professional Wrestling

 * After Booker T became "King Booker" in June of 2006, he not only started acting like an Upperclass Twit but apparently underwent a personality disorder of some sort that caused him to forget everything he had experienced as Booker T. When he saw Edge backstage, for instance, he would demand to know who he was - despite having bitterly feuded with Edge just a few years earlier. At other times, however, the old Booker T persona would reemerge and he'd once again speak in his stereotypical "Harlem" accent.
 * Also might apply to the many wrestlers who underestimate Rey Mysterio, Jr. after he has already beaten them! John Bradshaw Layfield definitely counts (and, in fact, this trope ultimately cost him his entire career), but, shockingly, also perennial babyface Shawn Michaels, who once taunted Mysterio to go back to the locker room because "Hornswoggle isn't out here yet!"

Video Games

 * Phoenix Wright of Ace Attorney. In case 5 of Ace Attorney (the first game). He shows himself to be a competent and clever lawyer, almost to Badass level. In most other cases (i.e. when he has a sidekick, excluding 1-4 & 2-4), he shifts from The Ditz to nearly Too Dumb to Live. Whether these are extreme cases of Obfuscating Stupidity or not is debatable, but the fact remains that while he cleverly outwitted the, only to revert back to dumbass rookie status by the next game.
 * That's because case 5 was tacked on for an Updated Rerelease.
 * Natalia from Tales of the Abyss. She's a bit spoiled, but otherwise elegant and conscious of her responsibilities as a princess. This doesn't stop her from believing every single tall tale that Anise tells her, including the ones about Van's eyebrow powers. Yeah. Eyebrow beams.
 * Probably the best explanation for Prince Amiti in Golden Sun Dark Dawn, who zips back and forth between being the Meta Guy and being The Ingenue, sometimes within a single scene. For instance, his knowledge of current events and the geography of Ei-Jei includes Champa pirate attacks, but apparently missed the extreme poverty of Champa that drove them to piracy in the first place, leading him to offhandedly condemn the ones begging his friends for help.

Webcomics

 * Celia of Order of the Stick gives this vibe. The first time we see her, despite the protections of the castle, she's uncomfortable at the growing dangers of her job and was a sentence away from ditching it. Then she's convinced by Nale that she's 1000 years into the future. Then she's a Savvy Lawyer. Then she fails to realize that humans don't have inherent lightning powers. Then she realizes that murdering their way through the hobgoblins would only alert them to the Resistance's presence. Now she's down again, as she's now incapable of recognizing the dangers of a really bad city, can't seem to grasp the bad intentions of the Golem maker, and just lost Roy's bones.
 * Maybe she's just really bad at Sense Motive, and thus easily fooled by Bluff checks. She's pretty smart otherwise, with the minor exception that she's not real clear on the differences between humans and sprites.
 * Fish Out of Water is the explanation that is invoked with her. It works better than you might think; she looks extra-foolish from our point of view since we know what she's getting wrong, but that's from our point of view. Of course, this is not to say it doesn't get done in an exaggerated way as well.
 * Same comic, different character: It's hard to tell if Elan in this strip (spoilers) is showing Ping-Pong Naivete, Obfuscating Stupidity, or just not believing a teammate would really harm him.
 * Elan does this pretty often; he usually isn't competent at much besides punning and tends to miss obvious things for the sake of humor, but he occasionally picks up on things that flew over the heads of his smarter friends for no apparent reason.
 * Joey from A Game of Fools is beyond a doubt the most sexually experienced of the main characters and his sheer ease at picking up women is frequently commented on (and shown). He also does stuff like this.
 * Grace from El Goonish Shive, even though she's smart and learns quickly. In part because she was raised by mad scientists and so has No Social Skills and remains facepalmingly naive in some areas, in part because she thinks messing with people is funny -- and it's not quite clear which case is which. One side of this was her smooth transition from Innocent Fanservice Girl to The Tease playing Innocent Fanservice Girl for her boyfriend.
 * The cast of Homestuck are all thirteen years old or about that age. Sometimes they act in extremely adult ways, but other times they remind you that they are children. John watches R-rated action movies and has a huge crush on Liv Tyler (and arguably Nicolas Cage) but when Karkat implies Vriska likes him, he freaks out and says he's never felt that way about anyone before.

Web Original

 * The Nostalgia Critic's intelligence and competence will vary depending on who he's with and if it's funny for him to be stupid or not.
 * This also happens to most of the reviewers that take part in the anniversary events. Part of it is for Rule of Funny and the plot, but a lot is because Doug and Rob Walker write the script and unfortunately aren't able to incorporate the character traits and continuities of all of the actors.

Western Animation
"Bart: So you're not pregnant? But we held hands.
 * In The Simpsons, due to being a 10-year-old boy, Bart fits the trope when it comes to things like sex, but that doesn't stop him from constantly making crude jokes and innuendo. In one episode, Homer sat him down and they had The Talk, yet in a later episode, this exchange occurred:

Darcy: Wow, you really are 10."

"Bart: What a beautiful day. The sun is shining, the birds are singing, the bees are trying to have sex with them, or so is my understanding."
 * Also,

"Robin: "Starfire... where's the sofa?"
 * While this trope often applies to Bart, it should be noted that the episode where Homer gives him "the talk" takes place two years in the future. It wouldn't affect his knowledge of sex in the current day.
 * Likewise, Lisa switches between world-weary cynicism and childlike naivete as the plot demands. In one instance, within seconds - she hurls a bucket of red paint at Krusty (who's wearing a coat made from some kind of animal skins), screams "Fur is murder!" then follows it with "When's the Krusty movie coming out?"
 * And of course, there's Homer, whose borderline retardation is seasoned with odd Author Filibuster moments of uncharacteristic eloquence.
 * Dexter from Dexter's Laboratory had his moments of stupidity. One example is when he thought he was going to die...because he had gas. We're talking about a boy genius that has done everything from go inside his sister's body to traveling to other planets using his inventions.
 * To "simulate" the gas buildup in his lab, he used a balloon to represent himself. In other episodes/shorts, he didn't know what the "strange protrusions" all over his body were (he had the chicken pox) and tried to do a search through the entire animal kingdom for the "species" known as... the girl.
 * Stewie of Family Guy has always varied between someone that apparently had an adult's knowledge of the world, frequently showing knowledge of popular culture and sex (he once knew how his parent were going to make another child and understood exactly how the biological function was), and being fairly erudite but possessing little knowledge that a baby wouldn't (he didn't understand his birth even after his first birthday).
 * Also Brian is a really smart dog that can talk and nearly graduated college, but when he was tied to a pole with a rope he couldn't figure out how the rope had gotten shorter after running around it over and over again.
 * In "Halloween on Spooner Street," Brian discovers Stewie shooting at "monsters" with an assault rifle, only to ask him how he doesn't know what trick-or-treating is. Stewie asks Brian how he doesn't know that his reflection in the patio window isn't another dog.
 * Rallo from The Cleveland Show is written in a similar way.
 * Fry of Futurama also falls into this trope, with both his overall intelligence (varies from slightly below average to Too Dumb to Live) and his understanding of new inventions in the future.
 * Zoidberg's medical knowledge qualifies. In some episodes, Zoidberg is unable to tell the difference between humans and robots or know if a human is alive or dead. However, in one episode, he is able to save a mortally wounded Fry by attaching his head to Amy's body, and then repairs the body.
 * Not particularly well, but hey.
 * Zoidberg's lack of medical knowledge was Scotch Taped recently. Apparently his doctorate is in art history.
 * Starfire from the animated version of Teen Titans. On occasion, it seems like she's learning and adapting to earth culture, only to be as naive as ever about it the next episode.
 * Hilariously played with in one episode with a blatant example of Obfuscating Stupidity:

Starfire: "Your Earth ways are strange to me. Please, what is this 'so-fa' of which you speak?""

"Reggie: Did you and Twister switch brains?!"
 * The boys on South Park, especially Cartman, are known to exhibit this.
 * "What's to understand? You get a boner, slap her titties around, stick it inside her and pee."
 * In "Marjorine" the boys thought the girls' paper fortune teller could actually predict the future, yet they were able to build and operate hi-tech machinery to study it with.
 * In "The Return of the Fellowship of the Rings to the Two Towers," Butters sees a good portion of what is apparently "the hottest porno ever made," yet many years later in "Sexual Healing" he sees a picture that includes a naked woman and becomes obsessed with it, even saying he's "never seen that part of a lady before!"
 * Specifically, he was obsessed by her pubic hair, something he probably hadn't seen in the porno.
 * Scott Tenorman Must Die - Cartman knows what pubes are, but not that you're supposed to grow them yourself (instead of purchasing them) and gets tricked into giving Scott Tenorman money and travelling to the "Pube fair" but is able to get revenge by tricking Scott Tenorman into getting his parents killed and then eating them.
 * Almost the entire second season of Drawn Together was dedicated to doing this with half-retarded Ensemble Darkhorse Captain Hero. The sheltered Princess Clara is an equally big offender.
 * XR from Buzz Lightyear of Star Command is savvy enough to sneak into a large casino and cheat it out of a substantial amount of money, yet he willingly hands over all his petty cash to a street hustler.
 * In My Life as a Teenage Robot, Jenny's childish naivete and Brad's constant hovering between a savvy, nonchalant, typical teenager and a brash, bullheaded, over-eager, hero-wannabe.
 * SpongeBob SquarePants and his best friend Patrick also fall into this category. Spongebob varies from being pretty smart to being completely clueless that Squidward doesn't appreciate his company (although his problem may be more naivety than lack of intelligence). Patrick varies from being a Genius Ditz to being Too Dumb to Live. And while Spongebob is usually smarter than Patrick, there are a few episodes where Patrick is actually the smart one.
 * Hank Hill has this about certain issues. In one episode he mentions a bank teller who is "in between genders" indicating some sort of awareness of the issue, in another when Peggy tells him that her new friend Carolyn is really a man (drag queen though as opposed to transgendered) Hank is genuinely baffled by the very concept, reacting with "Now wait a minute, that doesn't make any sense!" and continues to think of Carolyn as a woman for the rest of the episode, even going so far as to believe that, without her female clothes, she must be "Carolyn's boyfriend."
 * Perhaps he knows, but he's in denial?
 * The eponymous character on Jimmy Two-Shoes goes from being an optimistic Straight Man to a Dumb Blond depending on what's needed for the story.
 * Both Fanboy and Chum Chum cater to this in various episodes. In one instance they're ridiculously annoying someone with their ADD-riddled antics, and later they're acting perfectly normal, usually when having to deal with a problem caused by someone that's not them.
 * Ickis of Aaahh Real Monsters.
 * Otto and Twister from Rocket Power, with Twister being more the naive one. One particular episode lampshades this in effect; the gang convince Eddie (Prince of The Netherworld) to skate in his empty pool as long as they keep it to themselves and leave before his parents get home. Twister, for his part, keeps quiet, even when his brother Lars comes to make mischief. Otto on the other hand, kept bragging about it to strangers like it was a party, even to Lars. Reggie's What the Hell, Hero? one liner sums it up perfectly.


 * Animaniacs has Skippy Squirrel, who switches between an innocent Foil to his Aunt Slappy and a companion to her shenanigans whenever the episode calls for one or the other.
 * Sector V from Codename: Kids Next Door. Justified, as they're all 10.