Flushing Toilet, Screaming Shower

"... a propensity, while in use, to turn instantly beastly hot or blindingly cold upon you, depending on whether your neighbor turned on his cold or his hot to deprive you of a necessary complement in the shower you had so carefully blended."

- Lolita by Vladimir Nabokov

Bob flushes the toilet while Alice is in the shower. Alice screams and curses, unprepared for the sudden increase in water temperature. Or perhaps Alice turns on the washing machine while Bob is in the shower, causing Bob to experience a precipitous drop in water temperature. Can be done deliberately or by accident, but the result is still funny -- provided it's not happening to you. Can also be done by turning on a faucet elsewhere in the house, which has the advantage of not prematurely giving away the game if you are deliberately pranking someone. Usually deployed as a comedy trope, often accompanied by a quick shot of the Oh Crap expression on Alice's face when she hears the unmistakable sound of a toilet flushing.

Truth in Television as most shower valves mix hot and cold water to achieve the desired temperature so anything that diverts either hot or cold water will result in a sharp temperature shift in the opposite direction. Note that this was always a regional trope as it depends upon the central water heater practice common in Western plumbing design but not always found in other cultures. Rapidly becoming a bit of a Discredited Trope in Real Life since the introduction of pressure-balanced shower valves specifically designed to prevent this from happening. Such "anti-scald" shower valves are even required by law in some places, especially in commercial buildings like apartments, hotels, and dormitories. Nevertheless, if you have the (mis)fortune of being in a house or building with old plumbing, this trope is still doable.

Advertising

 * A Sensodyne advert features a woman turning on a tap. The man in the shower shrieks.
 * A Zoo Tycoon commercial shows this happening to a woman. Thing is, though, the one flushing the toilet is an elephant.
 * A Dutch commercial for the Army (Fit/Unfit) had two ten-year-old girls giggling as they turn on the faucet, one commenting after a bit "I don't hear anything". Cue a guy manfully enduring the cold as he soaps up and scoring a "Fit" in a multiple choice box. Watch here.
 * Happens in a Philishave advert to an opera-singing man in the shower.
 * A video game commercial shows Predator doing this to the Alien, complete with the latter's trademark hiss.

Comic Strips
"Garfield: Isn't science fun?"
 * Garfield does it to Jon to show Odie how the pipes in the house are all connected.


 * One FoxTrot strip has the Roger singing "Burning Love" in the shower at an obnoxious volume, prompting Andy to tell Jason, "There's a valve in the basement marked 'Cold Water Shutoff'..."

Films -- Live-Action
"Howard: Why do you always find that so funny?
 * George does it to his brother, Howard, in Two Weeks Notice.

George: It's very hard to say."

"Quint McHale: I'm going to take a shower. You know what that means?
 * Katherine does it to Sebastian in Cruel Intentions 2. Only difference being he slips without screaming.
 * Gina Davis' Hot Scoop character in The Fly. Her Jerkass publisher/ex-boyfriend breaks into her house and takes a shower while waiting for her.
 * From McHales Navy:

Roberto: Don't flush."

Literature

 * Neal Stephenson's early work The Big U has one student getting revenge on his former roommate by getting a small army of friends and other acquaintances, synchronized by a TV news broadcast, to do a big flush that actually destroys the plumbing system in an entire wing of the arcology-university. Was also coupled with supergluing shut the door to the shower stall, and then setting a "poorly insulated" electrical appliance in front of the expanding pool of water.

Live-Action TV
"Lois: You flush the toilet, I open the curtain!"
 * Attempted by Reese in a cold open on Malcolm in The Middle as his mother was taking a shower.


 * Done purposely by Alan when Charlie and his girl are in the shower in Two and A Half Men.
 * In The Mighty Boosh, Bollo flushes the toilet, melting The Hitcher, who is in the shower-like Fountain of Youth.

"Boy: Want to hear a joke?
 * ''Grace Under Fire": One of Grace's daughter's little friends is chatting with Grace, despite the fact that she's trying to shower in peace.

Grace: (sighs) Sure.

Boy: What did the man say when he fell off a cliff?

Grace: I don't know; what?

Boy flushes toilet. Grace screams.

Boy: That's right! (Runs away)"

Radio

 * Played with in the sketch Anthropomorphic Shower from That Mitchell and Webb Sound.

Video Games

 * In The Sims 2, if one Sim flushes the toilet while another is in the shower, the second Sim will jump out of the shower, run over to the first Sim and yell at him in Simlish.

Web Comics
"Mike: What the fuck is wrong with you!?!"
 * It is revealed in one of the Penny Arcade podcasts that for the entire time they lived together (a period of "at least a year"), Jerry (Tycho) would wake up early and turn on the taps to allow all the hot water in the apartment to run down the drain. The moment where Mike (Gabe) learns why he didn't have a hot shower during the whole time is priceless.


 * The episode is for the strip "Doctor Feelgood". Strip. Podcast. Story starts at about 17:10, but they whole thing is really funny.
 * Done once in Fur Will Fly.

Western Animation

 * Done on The Simpsons twice:
 * Season six's "Bart vs. Australia" -- Bart is trying to get the toilet water to go counterclockwise and repeatedly flushes the toilet. Meanwhile, Homer is in the shower and keeps screaming "Hot-cold-hot-cold-Who's-doing-that?!"
 * Season twelve's "Tennis the Menace" -- Bart turns on the kitchen faucet and Homer (once again in the shower) screams, and to tunes such as "Mary Had a Little Lamb".
 * Grandpa's hated, visiting sister does this to him in Hey Arnold
 * In Phineas and Ferb episode "Backyard Aquarium", this was done with a hose in place of the toilet.
 * Shown as one of the many pranks Huey, Dewey, and Louie pulled on Donald that got them on Santa's naughty list in Mickey's Twice Upon a Christmas.
 * Done in one Robot Chicken sketch: a girl flushes the toilet, and her father is scalded.
 * Done in Channel Chasers, with Cosmo being on shower and Wanda Flushing the toilet. Fridge Logic hits when you remember that they are a magic shower and magic toilet, so, not interconnected.
 * Slinkman from Camp Lazlo deliberately does this to Lumpus in "Slugfest".
 * Rallo does this to Cleveland Junior on The Cleveland Show. To add insult to injury, he takes a picture of Junior naked and presents it in a slide presentation, which causes Junior to get kicked out of the scouts.

Real Life

 * It happens. With old water heaters, ill-timed laundry, or what have you.