A form of Sexy Discretion Shot where a vehicle or other small enclosed space is shown moving vigorously to show that its occupants are "moving vigorously" too. (A common subversion is to then show that the vigorous activity in question was not the one you were thinking of.)
Compare Right Through the Wall.
- In an episode Yondemasu Yo Azazel San, this can be seen as a gag when Azazel's searching for Beel.
- The famous Peugeot 207 commercial with ladybugs.
- An Australian commercial had a police officer seeing a rocking car and going to investigate, only to find a solitary male using the advertised car cleaner.
Officer: Can't you do this at home, sir?Driver: My wife doesn't understand me.
- At least one mattress commercial begins with a view from under the bouncing bed, only to reveal someone on the bed trying to swat a fly or dancing to music.
- An Australian commercial for a mobile mechanic had a police officer investigating a vigorously rocking car only to discover the young female driver attempting to disengage the stuck handbrake.
- Averted in this Guinness commercial which shows a lucky woman having a foursome with three guys.
- In the early Jim Carrey movie Once Bitten, a coffin is shown rocking to show that the hero's girlfriend is finally doing the one thing that would end their current problem...
- Subverted previously when, out of the plethora of other cars at the Make-Out Point, Mark's ice cream van was the only one that wasn't rocking!
- Big Fish has a rocking trailer, but it turns out there's just a Hell Hound inside.
- Batman Returns has Penguin having way too much fun causing havoc with the remotely hijacked Batmobile, such that his trailer is rocking hard enough for any onlookers to think there's something else going on in there.
- A van is rocked this way in the Mystery Science Theater 3000 feature Hobgoblins, much to the hosts' disgust.
Tom Servo: They made love in their Chevy van, and that's not all right with me.
- Don't forget that the car made cartoon bouncing noises with each bob.
- Occurs in the opening of Idiocracy.
- Parodied in Scaramouche when the actual activity involves rather more being hit with frying pans.
- Used in the film version of Harry Potter and the Goblet of Fire in a carriage. Snape comes a knockin'.
- Titanic (1997): Inside a car loaded into the cargo hold of a cruise liner.
- Subverted in Whip It, the dad's car is seen doing this, accompanied by loud shouts from the dad. Turns out he's watching a particularly exciting football game.
- Salome's Last Dance (1988). As Salome starts her famous dance, the woman playing Herodias jumps into a crate with a beefy stagehand. Another stagehand sits on top, trying in vain to have a enjoy of wine while the crate is jumping up and down beneath him. Eventually the lid opens and a finger beckons him inside as well. As Salome's dance works to its peak, we briefly cut to the crate shaking wildly from the action inside.
- In episode 8x11 of Supernatural, "LARP and The Real Girl", as quoted above, though Charlie and Gilda were only making out.
- Also Tara's trailer at the end of 2x18, "Hollywood Babylon". Go, Dean!
- In 9x02, this also happens, but there isn't any sex going on, just killing. The guy was shown to be a vampire, but he wasn't the one doing the killing.
- On Bones, Booth and Brennan went undercover as circus folk, and to pretend they were a couple, they rocked their trailer back and forth to make it look from the outside like they were doin' it.
Circus Manager: Gotta give 'em points for stamina.
- Subverted in Mama's Family. In the episode "There Is Nothing Like the Dames", Thelma is trying to impress a small group of snooty upper-class women with a backyard dinner so they will let her join them. Unfortunately, Vinton and Naomi's trailer sits in the driveway, an obvious eyesore. On top of that, during one scene, the trailer starts rocking, horrifying the women... until Thelma finds out that Vinton was only trying to fix a broken table leg.
- Has happened several times on My Name Is Earl, such as Earl bringing in young Amish women to "show them a good time," and when Joy was cheating with Darnell.
- Pushing Daisies: In the second episode, there's a flashback of the Victim of the Week, a car safety tester, meeting his girlfriend, a promotional model for the same car company. This is followed by the display car in the showroom rocking back and forth, with the windows steamed up. Bonus points for the car being on a turntable.
- Also referenced in the second episode of season 2. Chuck notices the bumper sticker "Mimes do it with imagination" on a van just before they open it to find a dead mime. Emerson comments that the bumper sticker should have said "If this van's a-rockin', I'm being murdered."
- Seinfeld. In one episode, Jerry gets a van from an old friend. Elaine suggests that Jerry should outfit it with one of the troponymous bumper stickers. Also, near the end of the episode, Jerry and George catch George's parents rockin' the van.
- That '70s Show: Kelso: "If this van's a-rockin, we're inside doin' it!"
- Buffy the Vampire Slayer. Giles and Buffy's mother Joyce end up making out on the hood of a police car. The camera then pans over the car which starts rocking. A few episodes later it's confirmed they did have sex on the hood of the car. Twice.
- Community references this as Troy and Abed show new roommate Annie through the apartment - at their bedroom Abed plays with Ho Yay saying "If the room's a-rocking please come a-knocking because there's probably something terribly wrong."
- When Alison and Chad are going at it in Orphan Black, and one of her friends hurriedly herds her kids away.
- The Professionals. In "Servant with Two Masters", Bodie has a thug Bound and Gagged and throws him in the back of his car for safekeeping. Then Doyle comes along and finds the vehicle rocking as the thug struggles to free himself.
Doyle: Don't tell me he's found a milkmaid?
- Midsomer Murders: In "Country Matters", The Vicar confesses to meeting her (married) lover in his van in a field. Although she claims they were just talking, the flashback shows the van start rocking almost as soon as they get in.
- A less explicit version is in Grabbed by the Ghoulies, where the hero is sometimes chased by walking coffins that conceal plump, amorous vampire girls. If one catches him, he's yanked inside, and the coffin rocks for a few seconds (With ♥s drifting out and everything) before letting him go.
- Pretty much all sexI mean "Woohoo" done in The Sims games.
- Tony Hawk's Underground has one... across the street from a strip club.
- Subverted (though not in the usual way) in Questionable Content.
Pintsize: If the router starts a-rockin', don't come a-knockin'!Pintsize: ...Actually, if the router really does start a-rockin', do you think you could weight it down with something heavy? I don't want a cable to come loose and disconnect me.
- Subverted in It's Walky! when Walky and Joyce try to convince Joyce's grandchild-obsessed mother that they are having sex: the two of them simply bounce on the bed loudly like the overgrown kids they are.
- The gag itself is subverted when Joyce has an epiphany about why the two of them hadn't slept together yet.
- Tycho Brahe: Mr. Coulton? Um I know the trailer is rocking, and I really shouldn't knock in this instance, but... they need you for sound check. They want to check your sound.
- The trope is also seen in action in an early Vampire Cheerleaders strip.
- There was a Getting Crap Past the Radar version in 2 Stupid Dogs. The two dogs went to a Drive-In Theater, and every car around them was rocking. Even the one on the screen!
Little Dog: (complaining about the movie) This is caca! Why do people come here?
- Referenced in Animaniacs, where the Warners drop in on Dr. Scratchensniff and his date. Eventually, they start bouncing around, causing the car to jump as well. Outside, you see a mother forcibly turn her young son's gaze and push him away. *mwah!* G'night Everybody!
- Subverted in The Simpsons:
- Homer: Son, I've had some of the best moments of my life in the back of a car.(cuts to a picture of a rocking car)Young Homer: Oh yeah! etc(Interior shot of car reveals he's eating junk food)
- Played Up to Eleven in the episode where Homer visits Marge in prison: when Marge jumps on Homer, the trailer gets knocked over. With the only door facing the pavement.
- A helicopter being piloted by Barney also does this in midair when the woman he's he rescued, who was once his high school sweetheart, decides to give him some Pity Sex even though they both know a real relationship isn't in the cards.
- In Total Drama Island, Owen and Heather share a canoe for a challenge. Owen tells the other contestants, "If you see this boat rockin', don't come a-knockin'." Heather, who does not find Owen attractive, expresses her displeasure by smacking him on the back with her paddle.
- On The Venture Bros., The Monarch and Dr. Girlfriend first have sex in a car. They even manage to steam up the windows enough for the Monarch to write on them.
- Suggested in the Justice League episode "Eclipsed", where Flash uses the royalties for his energy-bar endorsement to buy a van. When Green Lantern asks why Flash, of all people, would need a van, he clicks a remote control that causes it to start rocking, and then shows off how the back is outfitted with a couch, stereo, and lava lamp like a mobile bachelor pad.
- In Futurama, Fry gets a Hippie Van and tells the rest of the crew, "In light of the fact that it's not a-rockin', I invite you to come a-knockin'."