Locked in the Bathroom

Whenever a character becomes upset at another character in a comedy, they'll usually lock themselves in the bathroom. Alternately, a character may lock themselves in the bathroom while being pursued to "escape" from their pursuers. The other characters will usually try negotiating with them to convince them to come out. Things usually get interesting if another character needs to use the bathroom.

In Real Life, the latter case is unlikely to offer the pursuee any protection depending on the reason he's being chased. Bathroom doors aren't meant to be much of a physical barrier and can be broken down with very little force. But on TV, the bathroom door is an impenetrable barricade. Once that door is closed, it can only be opened from the inside.

In a less dire case, such as a child having a tantrum, an effective solution would be to leave the upset individual alone and they'll get bored and come out eventually. Opening the door with an expired credit or gift card could also work if a more immediate solution is desired. But banging loudly on the door and shouting is way more fun!

Anime/Manga

 * In a chapter of the Keroro Gunsou manga, Keroro locks himself in the toilet to escape the wrath of Natsumi for messing with her favorite shirt.

Live Action TV

 * In Three's Company, Jack's date locks herself in the bathroom while Jack is having a food critic over for dinner. Mr. Furley, the landlord, arrives, announces himself as the manager of the building and demands that she open the door. When she refuses, Mr. Furley attempts to unlock the door with his credit card, which she takes when he pushes it through the crack.

Films

 * The Iron Giant: Hogart hides the giant's lost hand in the bathroom from his mother and Kent. After he gets it out the window, he pretends to be in the toilet when Mom and Kent force open the door.
 * In The Room, Johnny locks himself in the bathroom after his birthday party when he discovers his girlfriend and best friend have been having an affair.
 * In Neil Simon's Plaza Suite, a bride with cold feet locks herself in the hotel bathroom on her wedding day.
 * In The Kid, The Musical of the book by Dan Savage, the song "Terry..." is an attempt to coax Terry out of the bathroom after a fight.
 * In a cross between this and Locked in a Room, in Can't Hardly Wait Kenny (Seth Green) and Denise (Lauren Ambrose) lock themselves in the upstairs bathroom...and can't get out because the door's broken.
 * The Shining: I think the female protagonist locks herself into the bathroom to defend herself when Jack goes crazy, but I can't remember too well.
 * Then he axes the door down and delivers a creepy one liner, I believe.

Literature

 * In the Vorkosigan Saga novel Komarr, Nikki locks himself in the bathroom and refuses to go to school the morning after he learns that he's a mutant; Miles ends up talking him out.

Newspaper Comics

 * In one Calvin and Hobbes strip, Calvin takes Rosalyn's science notes when she is babysitting him and locks himself in the bathroom with them, threatening to flush them down the toilet.
 * Lizzie locked herself in the bathroom once in For Better or For Worse when she was very young.