When Alice and Bob both Cannot Spit It Out or have had an Unresolved Sexual Tension for a long time, occasionally fate helps a little by making one of them trip for some reason (often a fight) and fall on the other. They may both lose their footing and fall to the ground, or the standing one might brace the impact against a wall. Either way, awk-ward.
In some cases, they will separate and apologize, or Alice will scream and slap Bob, calling him a pervert. But if this trope is in action, neither will happen. By the magic (and surprise) of their sudden proximity, they will fall silent. They'll look intensely into each other's eyes, forgetting their fight entirely. Everything around them will fade, and their lips will slowly get closer, before locking into a True Love's Kiss. If there is no immediate kiss, it will at least be a Near Kiss, and probably an Aww, Look! They Really Do Love Each Other moment.
Compare Crash-Into Hello, which has little chance to result in a kiss for obvious reasons.
A Sister Trope to the less romantic and more comic Suggestive Collision, which can result in Marshmallow Hell or Thanks for the Mammary but is much less likely to end well. Compare Meet Cute, which introduces a future relationship between two characters. Also see the logical conclusion, Official Couple.
- This happens to Erza and Jellal in Fairy Tail. Although it's unclear whether they actually kissed or not, it's the first time they express their mutual love so clearly.
- My Monster Secret: Akane tries to make a use of this trope when Youko and Asahi are locked in the former's room by sending a sleepy Youko onto Asahi with a spring, or literally tilting the entire house so that they fall on each other. All her efforts are in vain.
- The Lion King does this during the "Can You Feel The Love Tonight" montage with Simba and Nala tumbling down a hill.
- In The 39 Clues, Ian Kabra rescues Amy Cahill and, in the process, somehow falls on top of her. This is quickly followed by a kiss, although the Relationship Upgrade doesn't last long.
- I.Q.: Thanks to a "helpful" Uncle Albert, Catherine winds up playing out this trope with Ed after repeatedly falling into his lap on a sailboat.
- In Smallville, Clark and Alicia have one of these, only to be interrupted by Alicia's psycho ex-doctor.
- During Buffy the Vampire Slayer's amnesia episode, "Tabula Rasa", Willow and Tara fall on each other and share a moment.
- The first overtly shippy moment between Arthur and Guinevere on Merlin involved Gwen throwing herself on Arthur in a bid to save him from a gargoyle swooping down from above.
- In Katawa Shoujo, Emi's route has this three times. First, Emi crashes into Hisao while running in the hallways - their first meeting. Second, Hisao and Emi have a pillow fight which ends with him on top of her in bed, and his inner monologue comes to realize he has feelings for her. Finally, after they've started dating, the same thing happens again, but with Emi straddling Hisao, which escalates into a relationship-solidifying h-scene.