Fun thing to do

A fun thing to do is when you're in an elevator, and there's another person in there with you, if they get off first, right as the doors are leaving you start to say "hey wait you dropped....." but you time it so that the last thing they hear before the doors close is "dropped". Then you get off on your floor and they spend the rest of their day thinking OH MY GOD WHAT THE HELL DID I LOSE?!?!