How to Create a Prank Cup

There's a description here of how to create a prank cup using cling rap, several layers of cling rap and a rubber band. The more i read it, the more ah, my brain rebels against itself. Yes, i don't think spilling water on your teacher is a great prank. But i do love the little tip they've added at the inn here, which is to keep your teacher in a good mood after pulling this prank,. Have a towel and ea cup of coffee on hand for afterwards.