Not as bad as what happened to you, but there's a couple guys I work with and we prank each other to make the day more enjoyable. The one day we were doing finish work in a house so we had to take our shoes off. The one guy puts rocks in the other guys boots. He thinks it was me so I come to work the next day to a pouch full of saw dust. I grab a 1/4" piece of wood and cut it and drill it to fit on a license plate. In big, black, bolt permanent marker I write " I <3 COCK" and screw it on his front license plate. Buddy drove around all weekend before his neighbour asked him where he got the sweet license. His wife even saw it and thought it was too funny to tell him.