These two characters are not an Official Couple, but they're clearly headed in that direction. The question is when. Their Will They or Won't They? relationship has spanned three seasons, their Unresolved Sexual Tension is impossible to ignore, and you're just waiting for a Love Epiphany.
And then they kiss. This is a Game Changer, right? It has to be. Their entire relationship up to this point has revolved ignoring their obvious feelings for each other, and now that they've kissed, they can't ignore them anymore.
Except that they can.
Shows that rely on the Ship Tease between their two lead characters have to keep fans interested somehow. The relationship between these two characters has to continue to progress or fans will get bored, but the characters can't get together too soon, lest the show suffer Shipping Bed Death. These shows often rely on gimmicks that get fans excited and offer an illusion of progress while actually changing nothing, throwing people a bone to chew on while they sit through another two or three seasons of Belligerent Sexual Tension. Thus, the fake first kiss.
It was New Years. They were undercover. Someone lost a bet. It happened Under the Mistletoe. It was in a dream sequence or an alternate timeline. Maybe they thought they were about to die and they just needed to feel the soft press of someone else's lips against theirs one last time. The reasons are endless. The important thing is that there is a convenient reason for the characters to justify the kiss as the result of something other than their feelings for each other and never bring it up again. If the kiss significantly alters the relationship between the characters in some way, this trope does not apply. The Reset Button is key here.
This trope usually happens between the male and female lead of a TV show. The characters should have a long and dramatic would-be-romantic relationship. It usually occurs in a season finale, mid-season finale, or Wham Episode, like a real get-together would, but unlike an actual get-together, it may have been promoted ahead of time to draw an audience.
While there may be older examples of this trope, it didn't become common until the early 2000s, after shows like The X-Files and Friends popularized drawn-out Will They or Won't They?-style Romance Arcs between series leads.
See Also: Ship Tease, Subtext, Fanservice, Will They or Won't They?, Fake-Out Make-Out, Accidental Kiss, Alternate Reality Episode, Platonic Kissing, Fever Dream Episode. Contrast: Moment Killer, Ship Sinking.
- In Ranma ½ there's the "relationship" between Ranma Saotome and Akane Tendo, which is a Love-Hate Relationship. Officially they don't kiss (at least in the anime), but the first attempt was when both become the protagonists of the Romeo and Juliet against their will just to unify them. Finally the last scene when they both kiss comes true for all the rest, except for these two since Akane duct-taped Ranma before kissing him◊.
- Happens several times in Promstuck, Lampshaded and played for laughs. John kisses Karkat three times with extremely flimsy excuses without realizing his attraction: in gym class as "CPR", during a theater rehearsal due to "the magic of theater" (they were both tech staff), and another time while drunk "to practice for when we have girlfriends".
- In Plan B, Bruno and Pablo manage to kiss three times while staying totally platonic Heterosexual Life-Partners. The first two kisses are done while they're drunk and playing up their Gay Bravado for an interested female friend and the third one is a Practice Kiss done to help Bruno get ready for a definitely-not-made-up-at-all acting gig that requires him to kiss another guy.
- Bakemonogatari: In a later arc, it is revealed that protagonist Koyomi's youngest sister, Tsukihi, is not his sister at all and is actually a divine baby cuckoo. At one point, the demure Tsukihi is upset and Koyomi tries to calm her down with a kiss. Tsukihi (who doesn't know she's not his sister) is naturally Squicked out about her Sacred First Kiss being stolen by her brother. He tells her don't think of it as a "real" first kiss because he's just a pervert.
- Chronicles of the Kencyrath: Jame and Tori are destined to be the Official Couple, but they have a lot of emotions and issues to work through before that can happen. They already had a Bid Damn Kiss in a magical house, in the middle of a volcanic eruption then Tori freaked out and ran away. No gimmicks, no plot devices, just emotional baggage and not being ready to deal with it yet. So he pretends it never happened, and Jame goes along with it out of tact. (And while it's not a dream or alternative reality, it's in a magical house that kind of makes it feel like it is, which makes it easier to pretend it wasn't quite real.)
- Strike the Blood: Deuteragonist and main love interest Yukina has her first kiss with Kojou because Kojou is a vampire whose powers only activate with sexual arousal (although Yukina also in love with him, but denies it). During the incident in question, the two of them are trapped underneath layers of ice and facing certain death along with the astonishingly-beautiful La Folia. La Folia (who is also hot for Kojou tries to kiss him to get Kojou's power to awaken, but Yukina stops her and does it in her stead.
- To Sail Beyond the Sunset: For her first sexual encounter, Maureen chooses Chuck Perkins, a classmate she has no romantic feelings towards, as her partner. They kissed before doing the deed, and though Maureen greatly enjoyed it, she did not fall in love with him. Even as their relationship turned sexual, they never fell in love despite caring for each other.
- Bones did three of these between Brennan and Booth.
- The first one was in the mid-season finale of season 3, The Santa In the Slush, where they were coerced into kissing Under the Mistletoe.
- The second one was in the fourth season finale, The End in the Beginning, an Alternate Reality Episode where they were married nightclub owners. Both scenes appeared in the trailers for those episodes. In reality, Brennan and Booth don't get together until the end of season 6.
- There a questionable third instance in The Sum in the Parts of the Whole, where Brennan and Booth kiss in a flashback. However, due to an actual kiss that also occurs in that episode, the status quo does change going forward.
- Buffy the Vampire Slayer does this with Spike and Buffy. Their first actual kiss was well before any actual attraction existed between them back in the season 4 episode Something Blue, as they were under the influence of a spell.
Castle: We kiss and then we never talk about it. We nearly die frozen in each other's arms, but we never talk about it.
- The series did one in the season 3 episode, Knockdown. Castle and Beckett kiss in order to appear less suspicious while trailing a suspect. Pictures of the kiss were circulating in the media over a month before the episode aired. The characters finally get together a season and a half later.
- Castle lampshades this in the season 3 finale:
- Doctor Who under Russell T Davies did this with the Doctor and nearly every companion. The ninth Doctor and Rose lock lips in the series one finale as the Doctor gives Rose a timey-wimey version of the kiss of life. In series two, the tenth Doctor gets kissed by Rose's body while it's being occupied by the villain of the week. The Doctor kisses Martha in her very first episode as part of a ploy to confuse an alien DNA scanner. Even Donna, who was always very clear that They Won't, gets in on it, kissing the Doctor in response to his demand that she do something shocking and unexpected.
- Farscape did this twice in the first season, in the episodes, The Flax and A Human Reaction. In both situations, John and Aeryn thought they were about to be killed.
- Ross and Rachel in Friends had their first kiss a few episodes into the first season. Newly-independent Rachel is with Ross at the dry cleaner's when a woman there tries to steal Rachel's cart, and she responds by getting inside and announcing she'll have to take her with her. The woman relents, and Rachel, exhilarated by her victory impulsively kisses Ross, who she does not know already has a crush on her.
- In NCIS, Tony and Ziva kiss and have a simulated sex sequence while undercover as a couple. The episode was aptly titled Under Covers.
- In The Office (US), Pam gave Jim their first kiss in "The Dundies" while drunk at a work party in a Chili's. Jim is surprised but clearly pleased.
- In an early example of this trope, The X-Files had Mulder hallucinate that he'd travelled back in time and met a World War II-era Scully in the season 6 episode, Triangle. Mulder and Scully also kiss to ring in the new year in the early season 7 episode, "Millennium". Theories differ on exactly when they actually got together, but the general consensus seems to be not before the end of season 7. In any case, neither kiss is referenced again.
- Avatar: The Last Airbender: Aang and Katara in "The Cave of Two Lovers", though it's ambiguous whether they actually kissed or not. Lost in the titular cave with their only source of light about to burn out, Katara suggests they invoke the story of two lovers who used to meet in the cave, trusting love to guide them.... By kissing. In a G-Rated Sexy Discretion Shot, their torch goes out right as they start to embrace each other... Then, after a couple seconds in darkness, the cave is revealed to be littered with crystals that glow in the dark, revealing the path to the exit.
- Danny Phantom is the Trope Namer for Fake-Out Make-Out, which Danny and Sam do twice before eventually getting together.
- In Miraculous Ladybug, Ladybug gives Cat Noir their first kiss to break him out of Dark Cupid's mind control, but she still doesn't figure out that he's the guy she loves and their relationship doesn't change.
- Another variant occurs in "Oblivio". Ladybug and Cat Noir are suffering from Identity Amnesia and discover each other's identities. Throughout the episode, the deduce from context clues details from their lives, including their love for each other. However, they realize that after defeating Oblivio, they will regain their old memories, but forget everything that led up to his defeat, including each other's identities. They kiss each other right before everything resets, which Alya manages to take a picture of and post it on the internet. Needless to say, Marinette is horrified when she finds out she consensually kissed Cat Noir while they had amnesia.
- Teen Titans: When she first came to Earth, the first thing that Starfire did was kiss Robin because her species can learn any language by touching mouths with a speaker. The two don't share a proper romantic kiss until the Grand Finale.
- In Phineas and Ferb, Isabella and Phineas get countless Ship Teases. The first time she kisses him is in the Made-for-TV Movie, and they are zapped with the Amnesia-Inator seconds later. The second one happens in Phineas and Ferb: Star Wars, but this almost automatically does not count due to taking place between their Elseworld equivalents. They finally get their Official Kiss as teenagers in the Flash Forward episode "Act Your Age".