Suggestive Collision

"(After being thrown back by the speed of the train) Hawkgirl: "Who's hand is that?" Flash: (Removes his hand from her chest) "Sorry""

- Justice League

When a man and a woman fall in close proximity and wind up in a sexually suggestive position. The guy ends up in Marshmallow Hell, or the girl lands sitting on his face. It could even wind up in an Accidental Kiss. The lighter versions will just end with the guy copping a feel.

Needless to say, this trope is particularly likely to affect the Accidental Pervert.

Regardless of the circumstances, nine and a half times out of ten, the girl will act like it was deliberate—whether that means screaming "Pervert!" and slapping him, or saying "My, my, you sure are forward." It mostly depends on which kind of girl she is.

Pops up a lot in anime. Seriously. A lot.

Likely involves Crash Into Hello, Thanks for the Mammary, and/or Funbag Airbag. Related to Not What It Looks Like.

The more serious and romantic Sister Trope is Literally Falling in Love.

Anime and Manga

 * In the 2003 anime version of Fullmetal Alchemist, Edward tackles the thief Psiren in an attempt to subdue her. Not only did they land in a rather suggestive position, but he accidentally groped her boob.
 * In Nogizaka Haruka no Himitsu, when Yuuto pushes Shiina out of the way of a falling sign, they wind up in a lewd position with an Accidental Kiss on top of it—just in time for Haruka to walk through the door.
 * Several times in Love Hina.
 * Also happens in Mahou Sensei Negima. Ken Akamatsu is a big fan of this trope.
 * Subverted in FLCL where it looks like Naota and Ninamori are about to have a collision kiss, but instead their foreheads collide violently with each other. Then again, like just about everything in FLCL, foreheads are often used as metaphors for sexual organs.
 * Code Geass: Kallen falls over Lelouch in a suggestive position, lampshading their uncertain relationship.
 * In another episode, Suzaku ends up falling on top of Shirley. However, in this case it is treated as a total accident by both parties, there is no Ship Tease involved, and nobody walks in to find them in this position, so its only relevance for their respective characters is, perhaps, that it emphasises that they are simply good enough (platonic) friends for it not to be a problem.
 * In Maison Ikkoku, Yusaku accidently kisses Kyoko when she falls from a ladder trying to replace a lightbulb.
 * In Neon Genesis Evangelion, there is an incident where Shinji Ikari falls with Rei Ayanami, causing him to land on top of her, with one hand on her breast. Being an Emotionless Girl, she doesn't react in any way.
 * Happens in Rosario + Vampire at the end of a fight between Kurumu and Mizore's Hot Moms (named Ageha and Tsurara, respectively). In an attempt to break the fight up, Tsukune is thrown at the two women—and lands in a very awkward position where his face is between Tsurara's legs and his hand is grabbing Ageha's chest.
 * Ouran High School Host Club
 * Haruhi has her First Kiss when slipping on a banana-peel, directly into the face of a pretty girl.
 * Tamaki ends up falling on her in a very suggestive position just as her father walks in.
 * Happens twice in Hanaukyo Maid Tai La Vérité episode 7. The first time was after an earthquake, Taro ends up lying face down on Mariel. The second was when the puppy Fenrir jumps on Taro and knocks him down, causing him to fall face down on top of Mariel again. They end up in an Almost Kiss.
 * Yu-Gi-Oh: Happens to Joey and Mai in the episode "Lights, Camera, Duel." Played with though, in that Mai fell on top of him because he was catching her as she fell from a dangerous height—and instead of going for the pervert-slap, Mai thanks him for saving her and calls him an "action hero".
 * In the episode which introduces Priscilla in Gun X Sword, she pulls Van out of the way of a collision with a rolling object, only to end up sitting on him in a very sexual looking position.
 * H2O Footprints in The Sand has the rare facesitting variation. With two different girls, in fact.
 * Sister Princess has quite a lot of moments of Wataru and a couple of his sisters falling accidentally (and otherwise on top of each other, ending up in very explicit positions.
 * Rito from To LOVE-Ru is seemingly incapable of walking in close proximity with a girl without having this happen. One time Yui even tried to avert this as she's well aware of his tendency for this, which naturally ended in her being the cause of the inevitable collision.
 * Rail Wars!: Episode 9 has Takayama getting the Marshmallow Hell version while operating a train car.

Films -- Animated
"Tuffnut: Ooh! Love on the battlefield. Ruffnut: She could do better."
 * Astrid falls on top of Hiccup, with her axe deeply embedded in his shield, while they're in the middle of dragon-training. Immediately lampshaded.

Films -- Live-Action
"Margaret: Oh my God! Why are you naked? Andrew: Why are you wet?"
 * In the classic adventure flick Romancing the Stone, Jack and Joan tumble down a muddy incline together, landing in a shallow pool—with his head between her legs.
 * In Transformers: Revenge of the Fallen, Mikaela lands face-down in Leo's crotch after a space bridge mishap. Subverted in that Leo notes he'd normally enjoy having a hot woman's face in his lap, but in this case he's worried she crushed something on impact.
 * This happens in Enchanted when Giselle falls out of the bathroom onto Robert.
 * In The Proposal, Margaret makes a nude run for the wardrobe from the shower. Andrew is also naked, getting ready to take a shower of his own. Neither is looking and they walk into each other at a fast pace. He ends up on top for her:


 * In The Naked Gun, Lt. Drebin jumps over the queen to save her from what he thinks is imminent danger. Of course, that's not what it looks like in the front page picture.
 * The lead in Eight Days a Week does this intentionally. He's spending the summer camped out on his true love's front lawn in an effort to win her over. She enlists his help in climbing down from her window to sneak out of the house to be with her actual boyfriend. He helps, but also takes the opportunity to invoke this trope, falling down with her on top of him in a different position each time.
 * Van Helsing has Hugh Jackman attempting to save Kate Beckinsale from a flying vampire that is carrying her off, which results in her landing on him with her legs around his neck.

Literature

 * Specter of the Past has that whole scene where Mara catches Luke and they have a conversation about his subversion of We Will Not Use Stage Make-Up in the Future before she asks if he's going to get off or is just getting comfortable.

Live-Action TV
"Buffy: The next thing I knew we're being attacked by this mutant ninja demon thing, and then we're on the floor on top of each other, and it's just really confusing being around you."
 * Doctor Who: This happens to the Eleventh Doctor and River Song in "The Time of Angels".
 * Also happens in a Torchwood flashback, between Jack and Ianto.
 * Stargate SG-1
 * In season 6 episode "Smoke & Mirrors", after they barely escape from a bomb, Agent Barret fall atop Major Carter in an awkward position. To protect her, or so he says.
 * Also happens in season 10 episode "Uninvited", where Teal'c falls atop Vala to protect her from a grenade he threw at a monster. Vala jokes that she's flattered but they don't have the time.
 * Buffy the Vampire Slayer: Buffy falls on top of Spike at the end of his "Rest in Peace" song in the Musical Episode; given Buffy's reluctance to acknowledge the UST between them, she responds by fleeing. In the next episode Buffy states that she'll never touch Spike again, only to immediately throw herself on top of him to save Spike from a hurled stake.
 * Angel: Also happens between Angel and Buffy in "I Will Remember You", and lampshaded by her later.

Video Games

 * In the James Bond game James Bond 007: Nightfire, Bond and the current Bond Girl fall out of a damaged ski lift and Bond lands on top. When the girl asks why he always lands on top, Bond replies, "Lower center of gravity?"
 * Grandia III has a scene like this with the two main characters.

Web Comics

 * In Ménage à 3, a collision among Gary, Zii and Yuki somehow ends up with Gary on his back, Zii sitting on his groin, Yuki sitting on his face, and the latter two facing each other.
 * The Order of the Stick: Haley tackles Elan from above to stop him from touching a magical gate—inadvertently putting the two of them in a suggestive position.

Western Animation

 * In Code Lyoko, a few of Ulrich and Yumi's martial art sparring ends up with them in a awkward position and blushing fiercely. Also in episode "Swarming Attack", when Yumi and Ulrich run into a building to escape a swarm of bees, Yumi falls on top of Ulrich.
 * Miraculous Ladybug; This has happened to Ladybug and Cat Noir several times. In fact, as the origin episode shows, it was how they first met.