In my office we play this game where you write something on a post-it like "bomb" or "cyanide" and stick it under a person's chair or under the phone or whatever. So if the person sits in their chair when there's a bomb under it they're out of the game, if they find the bomb before it can explode they're still in.

I can remember one time when a professor went past and asked why a student was on the floor, and he said without thinking "I'm checking to make sure that Mahmoud hasn't put a bomb under my chair again." The professor was horrified and the rest of us couldn't stop laughing.