me and a mate of mine were in the middle of a huge prank war, and while it had managed to remain light-hearted for a good 5 weeks, after he pulled a prank that led to my nose being broken, i decided it was time to take it up a level.
i knew that in a few days we had to do a presentation in our english class, and thought it might be fun to publicly humiliate him. so i got the idea from collegehumor (sorry zvue) so crush up viagra and slip it into his drink at lunch before english.
pretty disapointingly, his presentation went down without any surprise wood so to speak, but then after everyone had finished and the whole class was quietly working- were all scared shitless by an ear-splitting scream and my mate holding his cock with a painful and confused look on his face. he suddenly lept up and legged it out of the class, my terrified teacher running after him, and all of our 'wtf' faces out in force.
he wouldnt actually tell us all exactly what had happened (and im hoping somone here can shed some light on it (i may have put too much viagra in there)) but it did end the prank war. and i think i won.