The protagonist decides to do something mischievous, nefarious or otherwise verboten under the assumption that somebody is going to be out of town. For a plenitude of reasons (sometimes as little as "I just wanted to see you again.") you can bet your ass they're going to show up when it's more dramatically appropriate.
- Happens a few times in That70s Show. Once in a very early episode in which Eric goes to Donna's house in the middle of the night while her parents are away to find that they've come home early. And then again when Donna and Eric take advantage of having the house to themselves, when all of the other characters come home almost immediately, much earlier than anticipated. And yet again when Eric has "borrowed" his dad's car and relaxes, glad that he has so much time to clean up - but he learns that he only has forty minutes.
- Drake And Josh turn the house into an inn while their parents are away, and it becomes a monumental affair. The parents call the boys to tell them that they're coming home early. They clean it up in time, but get busted anyway.
- In Different Strokes the family comes home early from a ski trip or something due to bad weather. They arrive in the morning, and Mr. Drummond (who stayed home) has an, overnight female guest. This puts him in the awkward position of explaining her presence to Arnold.
- In The Hard Times of RJ Berger this trope occurs.
- In Body Double the protagonist comes home early to find his girlfriend having sex with another guy. They don't stop when he catches them.