Two characters, usually two characters sharing a large amount of animosity, get locked in a room (safe, elevator, etc.) and must spend the episode alone together. During which time they learn a new appreciation for each other. Usually a type of Bottle Episode, this trope is almost a requirement of any Sitcom that's been on for more than a couple of years. This is also an extremely common trope for playwrights, particularly for short two-hander plays. In addition to being an easy way to force conflict, it makes set design much simpler. See also Chained Heat, Rats in a Box.