Anyone have any good ideas for a GOOD senior prank??!

Anyone have any good ideas for a GOOD senior prank??

i was thinking about making hashbrownies and getting a bunch of people (myself included) to leave one on each teachers desk but i figure if we get caught were pretty screwed...and last years sr class just died their uniform shirts and had all their phone alarms go off at the same time...i didnt think it was that good...and please dont suggest anything about getting 3 farm animals and painting #1 #2 and #4 on them...or anything to do with farm animals in general...thanks!

please dont do that ( or anything with drugs) i know someone that put acid in the teachers coffee and they got in legal trouble.