Pranks can be a good time, also, pranks can be a bad time. This youtube shows a harmless and victimless prank that i do know.
edit: suggested to me that this victimless prank was a deep thought by jack handy many years ago and that i remembered devising this victimless prank with my friend Moe years ago but we probably had the jack handy thought deep in our brains. . Well, this suggestion is grasping at straws. Jack Handy clearly speaks of a pumpkin in this deep thought while my prank clearly involves a melon. *PUMPKINS ARE NOT MELONS!!*