typical prank, i took the doors of two guys i didn't like, and tied them together using a series of bungee coords, then proceeded to knock on both their doors. They both tried to open the door and obviously forced the other individuals door shut. The smart one climbed out his window, walked into the dorm and punched me, than sat with me as we watched the other guy try to get out of his room frantically.
We would throw cold water on each other (in little 6oz dixie cups) enough for the "oh haha" effect.. then my roommate got hit and he escalated it. He found out who hit him, filled up three 64oz cups of cold water, THREW IN ICE into one of the cups, then hit the guy in the shower. The first blast was like "whoa!, the second was like "OMG!" and the third with the ice caused a lot of pain from what i understood.
One time while a guy was going #2, refer to above prank, use imagination as to results.