Coitus Ensues

"Next thing I knew, TS returned to her house to find two women in black catsuits pointing guns at her. I didn't catch any of the ensuing dialogue, but it must have been pretty fucking convincing, because I looked away for one second and after I looked back, the three of them were having lesbian sex on the snooker table."

- Ben "Yahtzee" Croshaw's review of I Like To Play Games Too.

So you're enjoying a piece of fiction, and things seem to be coming along nicely. The heroes have gathered the necessary plot coupons, acquired the Sword of Plot Advancement and cleared a couple of side quests. Now all that's left is the encounter with the Big Bad...

...But then, the narrative comes to a screeching halt, takes a sharp right-angle-turn and treats us to two of the characters having sex. Because apparently the romantic subplot has not received a satisfactory conclusion as of yet, and what better way to clean up that loose end than with an extended sex scene?

This trope is, at times, logical in the sense that given what we know about the characters in the story, yes, it makes some sense that they would have sex at this time. Where it becomes illogical is that there's seldom any narrative purpose to show them actually doing the deed. Functionally, it does nothing to advance the plot if nothing particularly important happens while they're having sex, especially when compared with the far more efficient Sexy Discretion Shot.

Please note that the point of this trope is not simply complaining about the presence of sex in fiction, only when the plot comes to a halt so two (or more) characters can go at it purely for Fan Service. Deus Sex Machina and many of its subtropes can overlap with this trope if the particular details are only brought up immediately prior to the act. Compare also Strangled by the Red String, which is much like this trope, except with love instead of sex.

Anime & Manga

 * The anime movie A Wind Named Amnesia rolls along like a typical, navel-gazing, post-apocalyptic road film. Then right before the Gainax Ending, the main hero and his alien love interest strip and have sex with no romantic buildup to this activity whatsoever. (Granted, they spent most of the movie on the run from killer robots and savage humans and managed to bond somewhat, but the sex still feels as though it comes right out of left field.)

Comicbooks
""Are you cold?" "No." "Are you lonely?" "No." "Do you want to jump my bones anyway?" "Sure.""
 * Happens a lot with Moonstone in Ellis Thunderbolts and Dark Avengers, primarily because she's a manipulative sociopath who considers it the easiest way to get her hooks into her teammates while ticking off her boss.
 * It might be more difficult to play the manipulator against Norman freaking Osborn, or against his money.
 * This is also a tactic used by her teammate Daken. He'll sleep with both men and women to get what he wants.
 * The Dark Knight Strikes Again: Superman and Wonder Woman had sex for several pages for no real reason.
 * Played for Laughs in The Punisher MAX with Castle and O'Brien.

"Kori: You are boring me. Roy: Um, Jason's over there talking to himself. Kori: And we're here. Do you want to have sex with me?"
 * Some of the sex scenes in Watchmen are irrelevant, especially the one at the end with Dr. Manhattan watching.
 * Red Hood and the Outlaws, part of DC's "new 52," does this in its first issue, when Roy Harper/Arsenal is seeing if Koriand'r/Starfire remembers knowing him when they were younger.

Fan Fiction

 * The My Little Pony Friendship Is Magic fanfic "Progress: Luna vs. Threesome" includes the phrase "And then they all fucked!" immediately following a set-up for a sex scene between Luna and her two roommates. In context, it was actually a cut to Pinkie Pie talking to Twilight Sparkle about a porn DVD she got from Celestia. The actual sex is off-screen and integrated into the story more tastefully.
 * Another Friendship is Magic example. In Fallout Equestria it's a toss up which ones slows down the work more, several scenes of Littlepip and or the one scene of
 * My Immortal, of course. "We jumped on each other and started screwing each other" indeed.
 * Though Dark Secrets had been building up the romance between Draco Malfoy and Mary Sue throughout (in its own particular way, of course) the actual sex scene comes completely out of nowhere immediately after she's tried committing suicide. It's also something of a Big Lipped Alligator Moment, in that it's completely different in style from anything else in the fic, never gets referenced again and could be (in some versions has been) removed without changing anything.
 * This is often the case with many forum based roleplays.
 * And fandom-based Live Journal roleplays are guilty of it, as well. In fact, some threads are created with the sole goal of making the two (or more) characters involved have sex; at some point, the players will inevitably lose patience and think up some sudden excuse or trope to use to speed the process up. Sometimes entirely too much.
 * Became particularly noticeable in pre-game of Survival of the Fittest v4. Many, many characters had graphic sex scenes with varying degrees of lead-up, to the point where handlers often commented on and poked fun at it.
 * "They banged. The End"

Film

 * The many sex scenes in The Room, which were inserted just so Tommy Wiseau could have an excuse to see his own naked ass on the silver screen.
 * Admittedly, at least one of them was plot relevant. Ironically enough, it was the one without Tommy Wiseau's naked ass.
 * The sex scene in Uwe Boll's butchering of Alone in The Dark. Tara Reid's character shows up and just bones the main character. And they never speak of it again.
 * Also in his take on Blood Rayne. Only this time, it seems like Rayne was aroused by nightmares/memories of herself murdering a bunch of people.
 * Dutch movies, as a whole, have the reputation that every single one of them will have an illogical and unnecessary explicit sex scene somewhere around the middle. Excepting children's movies, this is largely true, at least in the "unnecessary" respect.
 * This reputation leads to a Every One Remembers the Stripper situation with a (for the most part forgettable) movie called Bride Flight having "sex" "frontal nudity" and "nudity" as the top keywords on IMDB despite only having one scene that features this.
 * Exactly the same thing happens with Spanish movies, specially after Franco died and censorship went dramatically down. The just-after-Franco age isn't called "Época del Destape" ("Stripping Age") for naught. Though that specific period is considered a bit of an Old Shame by now, there's still plenty of gratuitous sex in Spanish movies.
 * Also Spanish soap operas. Most soaps in North America go on during the daytime (i.e., when children are at school), on the basic channels. These ones are only on cable, and only after eleven.
 * Near the end of the Children of the Corn remake, the child cultists are having a feast, and afterward two of them start to randomly have sex as a part of some disturbing ritual.
 * In Cabin Fever, the last healthy man in the cabin finds the last healthy woman sitting on her bed, staring sadly out the window. She tells him that their all sure to get sick and compares the situation to a plane crashing, stating that "all you wanna do is grab whoever's next to you an fu*k them, because your going to die anyway." She gives the man a lingering predatory look and then suddenly we see her throwing him down on the bed (both competely naked) and screwing his brains out.
 * It's pretty likely that there's a line in Orlando Bloom's contract for Kingdom of Heaven that states that he gets to have a sex scene with the female lead, no matter how completely ridiculous it is in the context of the plot.
 * While having the financial partnership of the protagonists lead to a romantic coupling in Rollover was plausible enough, the first sex scene is in the first act when the two hardly even know each other. The other two sex scenes that follow in the second act are just as annoyingly gratuitous. One gets the impression that someone thought the financial apocalypse to which the film was building wasn't going to be enough to keep the audience's attention, and that the sex scenes somehow would. However, the sex scenes only detract from the story, and the movie would probably be a lot better without them.
 * According to some (probably most) reviewers, Supernova provides perfect examples of this trope.
 * Waterworld has an odd scene in which a young girl is captured and the main characters go save her... after randomly having sex first.
 * IIRC, the ship was crippled at that point, so they couldn't do anything to save her. It's just that right after they have sex, a Brick Joke from earlier in the movie comes to help them along (which admittedly, still counts as a Contrived Coincidence existent mainly so that they can have sex at this point and still save the day).
 * Any movie where Steven Seagal has a potential love interest, especially the ones directed by him..."And so the Lord said: Let there be Coitus!"
 * Watchmen has a very long, awkward scene of Dan and Laurie having sex. This was another case of "why did this have to be in the movie", as this was only dealt with briefly in the graphic novel, and the movie was already quite long even without it.
 * In the film version of 300, King Leonidas and Queen Gorgo make love the night before he goes off to battle. It could have been an appropriate scene, showing a fleeting moment of tenderness before a bloody war, but then it showed them going from missionary to doggystyle and it started getting silly.
 * Averted by most James Bond movies. While he certainly does bed a lot of women in his nearly two dozen films, the scenes always cut to something else before things get steamy. In fact, the only explicit sex scene ever shown is in Goldeneye between Xenia and the Canadian Admiral she was dating. But even then, she's inexplicably fully clothed (to avoid an "R" rating most likely), and the scene is shown because it's plot-relevant: she murders him during the act while an accomplice steals his ID.
 * Monsters Ball has this with its infamous sex scene. Not only does it add nothing to the story, but many viewers could have happily lived their lives without ever seeing Billy-Bob Thornton's pasty, bony ass.
 * There's one in Shark Attack 3: Megalodon.
 * Underworld Evolution has an awkward sex scene not too far into the movie immediately after the two characters meet the Big Bad.
 * Since Evolution is an immediate sequel (it literally takes place hours after the original ends), it could be argued that it's a culmination of the first film's Unresolved Sexual Tension brought on by the emotional stress of the events around them.
 * In Halloween: Resurrection, Donna just randomly decides to have sex with Jim, who she completely hated up until that point.
 * The third film Season of the Witch has Dan and Ellie randomly start kissing and having sex when they get to the motel room. Bear in mind they've known each other for less than two days.
 * Tom Atkins (plays Dan above) seems to make a habit of this. In The Fog he and Elizabeth hop into bed having met at best half an hour ago before they even know each other's names. The remake justifies this by making them an on-off couple.
 * The lesbian sex scene in Eko Eko Azarak might be viewed by some unkind souls as not being entirely essential to the plot.

Literature
"The zipless fuck is absolutely pure. It is free of ulterior motives. There is no power game. The man is not "taking" and the woman is not "giving." No one is attempting to cuckold a husband or humiliate a wife. No one is trying to prove anything or get anything out of anyone. The zipless fuck is the purest thing there is. And it is rarer than the unicorn. And I have never had one."
 * Fear Of Flying describes such sex scenes as the "zipless fuck":


 * Vlad's first encounter with Cawti. Usually, a recently-resurrected person has a very different first meeting with the person who killed them.
 * It was at least foreshadowed (the book started with Vlad griping about how assassinating somebody always makes him horny), and the suddenness of the jump into sex and relationship is noted afterwards. Neither really ameliorates the effect.
 * Guy Gavriel Kay loves gratuitous sex scenes.
 * In The Lions of Al-Rassan, an assassin has just killed a minor king and been exiled by his successor. Then the minor king's mistress and the mother of his two bastard sons shows up at the assassin's estate and Coitus Ensues. For no reason at all.
 * In Tigana, the main character suddenly gets to sleep with a duchess he just met, with the encounter being described in a great detail.
 * Neil Gaiman apparently decided that what American Gods really needed was three sudden bonking (with a twist) sequences, two of which were completely irrelevant to the plot, took place in a completely different locale, and involved characters who had not been seen or even mentioned beforehand. One sex scene was especially unexpected because it involved two men, a salesman and taxi driver, and gave virtually no indication that either was gay until a quarter of a page before the thrusting began. (Assuming everyone is straight, of course, and neglecting that the main barrier to such scenes in real life is ascertaining that the other guy is in fact gay enough too.)
 * The scenes with Bilquis and the djinn do serve a purpose, though - they show us how the former gods are making it nowadays, and exactly how un-glamourous, how far from godlike it really is.
 * Lo Mejor Que Le Puede Pasar A Un Cruasan has two sex scenes. The second one at least somewhat fits into the narrative. The first one, with the main character having sex with a prostitute... yeah, that one we could have done without. The movie adaptation even skips it.
 * Ben Elton is often guilty of this in his novels. One such scene in The First Casualty earned him a Bad Sex Awards nomination for the worst sex scene in literature that year.
 * In The Pale King, Ms. Neti-Neti is nicknamed the Iranian Crisis for a very good reason.
 * Near the end of The Steel Remains, Ringil Eskiath suddenly has sex
 * Stephen King's IT has two examples. First of all in the 1950 timeline . Then in the present Bill and Beverly hop in the sack together when staying at the Derry Inn. It would be a Big Lipped Alligator Moment if it weren't for Bev's childhood crush on him. Nothing really comes of it either as Bill goes back to his wife Audra and Bev is implied to get together with Ben and it's never mentioned after that.

Live-Action TV
""God, why do all my stories end that like this?""
 * The That 70s Show episode "Donna's Story" had Eric try his hand at writing. All his stories eventually featured the main characters (based on him and Donna) randomly having sex.


 * Played for Laughs in an episode of It's Always Sunny in Philadelphia. In The Gang's movie "Lethal Weapon 5" the plot stops so the evil casino owner (played by Frank) can have a long, drawn-out sex scene with his girlfriend. To the Show Within a Show audience watching the film, it's this trope. To us (and to The Gang) its clear that the sex scene was only there so Frank could get it on with the actress (a prostitute he hired specifically for the sex scene). And yes, Frank was really having sex with her.

Print Media

 * Mad Magazine parodied this in issue #132, which had an article on Academy Awards for sexual elements in films. One of the categories was "Best Director for a Sex Scene that Was Created Out of Nowhere". One of the nominees was a sex scene during a debate in the UN General Assembly.

Webcomics

 * In the first Ciem, chapter 18 is this. Some argue it fits the plot. Others say it interrupts pacing.
 * Chapter 2 of the book version averts this by making They Do a critical plot-relevant event that defines the protagonists' motives from that point onward.

Videogames

 * Both sex scenes in Fahrenheit (2005 video game): The first one being an optional encounter where, if you play your cards just right when your ex-girlfriend drops by at your apartment (offer her a drink, play your guitar for her and then kiss her), she and Lucas will have sex together. The second one, however, is much more Egregious:
 * There's also the fact that.
 * Fahrenheit's successor, Heavy Rain, contains an optional one near the end: with only hours left to save the life of his only son, Ethan Mars can opt to take a break and sleep with Madison Paige despite his many devastating injuries, the obvious waste of time, and little to no previous romantic chemistry between the two.
 * Fate/stay night offers an arguable example, with the overlap with Deus Sex Machina, where Rin doesn't mention that having sex is a way to recharge a Servant's mana until Saber's has all but run out. It is foreshadowed, but only subtly, and it's a long time before the reader figures out why she held that back.
 * Really, this is a somewhat universal Nasu thing. One gets the feeling that he doesn't really WANT to write H-scenes, and is only shoehorning them in out of some imagined obligation to the fanbase. This may have something to do with why they are so hilariously BAD that they tend to induce drinking games rather than arousal. ("Every time there's dialogue with an ellipsis in it, take a sip! Every time he mentions seafood, take a shot!")
 * The sex scenes in Dragon Age Origins. They are optional however, so one can hardly complain, and it becomes a Sexy Discretion Shot if you get it on with someone more than once.
 * And of course the game also has the excuse of already having quite a lot of random character interaction, so what's a sex scene or two in the mix?
 * A minor sidequest in Mass Effect involves doing a favor for a high class consort. As a reward, the consort gives Shepard a trinket and a few words of inspiration based on Shepard's past. If Shepard expresses dissatisfaction with the reward, the consort and Shepard have sex regardless of Shepard's gender and without input from the player.
 * Silent Hill: Shattered Memories has Harry and very randomly having sex on the boat near the end of the game with little build-up. Even Harry seems surprised it's happening (though he doesn't really complain). Sure, , but Harry himself shows little to no interest in her throughout the game and, most of the time, is genuinely confused as to who she is and why she knows him.
 * The unexpected, awkward and unconvincing sex scene in Mafia comes to mind.