You want to get rid of evidence that could be really hazardous your and/or others' health and/or reputation, but how and where possibly? A fire would be way too destructive, so how about the last place where people would be willing to look—down the toilet!
An example being when the police search a criminal's house, they generally look in every nook and cranny they can find. So, the criminal may try to just flush the evidence (typically illegal drugs, but can be other things depending on the Rule of Funny) down the toilet.
Success varies, with the worst case scenario being a clogged toilet and a potentially flooded bathroom. In fact, the FDA outright discourages doing this in the first place due to environmental concerns.
- Referenced in Lilo & Stitch 2: Stitch Has a Glitch, where Lilo deadpans to Stitch, "Next time, flush the evidence." Stitch responds by miming flushing a toilet and making a "ka-shush" noise.
- Monsters, Inc.: After he attempts to put Boo back in her room, Sulley gets some of her toys tangled around his person. He tries to flush them all down the toilet, but it gets backed up, so instead he hides them inside a locker, where they reappear later in the movie.
- Attempted but subverted (hilariously) in Angel's Mission; when the police raids a night club where a drug dealing is happening, one of the dealers escapes to the toilets with packets and packets of heroin with him, being pursued by the police, where he then locks himself in one of the stalls and begins emptying the drugs into the toilet while shouting at the cops outside, taunting them that they are helpless from stopping him from disposing the evidence... oblivious to a sign outside the stall that says "Toilet is Currently Out of Water. Apologies for Any Inconveniences Caused".
- Happens to Oscar in Enter the Void, during a drug deal at a club. The police start raiding the place and he heads for the toilet to flush down the drugs on him. A disgusting scene of him shoving the pills down the drain ensues.
- Goodfellas: Henry is furious and suffers a breakdown after his wife tells him she flushed sixty-thousand dollars worth of drugs down the toilet while the police raided his house with a search warrant.
- In The Man with One Red Shoe, the agents think Richard is doing this when he repeatedly flushes his toilet. In reality, they put his bathroom plumbing back together so poorly, he has to flush the toilet to get the sink to work.
- Psycho famously became the first film in history to feature a toilet flushing for including a scene where Marian tears up a note and discards of the remains this way.
- White Nights: A famous ballet dancer who defected from the USSR tries to hide his identity from Soviet officials by flushing his passport down an airplane toilet as his plane crashes in Soviet territory.
- In the fifth book of the Diary of a Wimpy Kid series, Greg goes to a lock-in at his middle school where a kid named Jeffery Chang brought a big bag of cheese puffs. Due to a ban on snacks, he locked himself in the boys' bathroom to eat them, but the adults caught on quickly, so Jeffery was forced to flush the cheese puffs down the toilet.
- The Drawing of the Three: Stephen King's gunslinger Roland meets Eddie Dean when a flight crew suspects Eddie of smuggling drugs and flushing the evidence down an airplane toilet.
- Beverly Hills, 90210. David is holding a knapsack full of drugs for a friend of his when Dylan arrives at his apartment to warn him the cops are on the way. They promptly flush everything down the toilet just in time. (In Real Life, it's highly likely the toilet would have clogged, given the amount they were flushing, as well as the plastic bags).
- Breaking Bad: During Season 1, Walt and Jessie are forced to kill their first rival drug dealers, Krazy-8 Molina and Emilio Koyama. Walt hides evidence of murder by dissolving their bodies into red slush using hydrofluoric acid. Jesse is disgusted, but finishes the job flushing the evidence, bucket by bucket.
- Parodied on the Thanksgiving Episode of Brooklyn Nine-Nine when everyone realizes what a terrible cook Amy is, they flush their food down the toilet to avoid telling her.
- Law & Order: SVU:
- During the episode "Poisoned Motive", drug dealer Earl Talley runs to the bathroom to flush his drug stash minutes before police arrive.
- The episode "True Believers" has a complicated rape trial where the perpetrator flushed part of the DNA evidence along with a condom.
- In "Mr. Monk and the Big Reward", a woman keeps coming in to confess to comically small crimes (such as stealing a pen from a bank). During one of her "confessions", she admits to getting rid of a body by flushing it. It turns out the "body" was her hamster's.
- In "Mr. Monk and the Rapper", Stottlemeyer, talking to Murderuss after circumstances implicate him in a rival's death, mentions having known him before he made it in music and reminds him that he tried to flush drugs several times to prevent Stottlemeyer from busting him.
- The Wire:
- The Season 2 episode "All Prologue" has D'Angelo Barksdale flush his drug stash down a prison cell toilet.
- During a raid on a brothel led by Detective "Bunk" Moreland, a gung-ho cop prepares to knock the doors down. Bunk stops him and asks what he's doing, and the other cop responds that he's going by standard procedure, to knock down the doors and enter rapidly before evidence can be destroyed. Bunk stares at him for awhile and then asks if the other cop thinks the brothel is going to flush the whores down a toilet.
- Referenced in Sam & Mickey's "Flying High":
Curly Hair Jail Girl: So you killed your ex in the bathroom, cut up his body into little pieces, flushing them down the toilet?Barbie: (also in jail) No, but I did do something far more sinister with him.
- In Chapter 5 of Danganronpa V3: Killing Harmony, Kokichi Oma's clothes are flushed down the toilet, to hide evidence of his and Kaito Momota's plan.
- In American Dad!, when Stan gets fired from the CIA, he takes up the job as a meter maid, much to his initial disdain. He soon discovers that collecting quarters for his own gain instead of giving them to the city earned him much more money that affords him and Francine a luxurious lifestyle. When an investigator knocks on their front door, Francine and Stan panic and start trying to flush dozens of quarters down the toilet when they think the jig is up.
- Bojack Horseman: A variation happens in "Ancient History"; Hollyhock still has bad memories of being drugged by Beatrice, causing her to dump Bojack's painkillers down the sink.
- Semi-example in The Loud House episode, "Sleuth or Consequences". When Lincoln is accused of flushing a copy of the Princess Pony book down the toilet, Lucy decides to help Lincoln clear his name so he can go to a comic book convention. Near the end of the episode, it is revealed that Lucy is a fan of Princess Pony, but she didn't want anyone to find out, given her goth reputation. She hid the book in the toilet, but Lincoln accidentally flushed it down, not knowing it was there.
- The Simpsons: In "Love, Springfieldian Style", Lisa as Nancy Spuggen and Nelson as Sid Vicious get hooked on chocolate as if it were cocaine or heroin. Their chocolate spree involves them snorting lines, cooking (melting chocolate powder on spoons), and flushing chocolate bars down the toilet.
- At least one group of dumb criminals tried to dispose of (a very large amount of) cannabis by attempting to flush it all down the toilet.
- British Serial Killer Dennis Nilsen's (considered the British equivalent of Jeffrey Dahmer) crimes were discovered when his drains were found to be clogged with human flesh.