Lethal way to get back at him:
What you need to do is challenge him to a fight at the TOP of a tall building. Go there and make him stand at the far end of the edge. Stand directly infront of him but at a big distance. When you say fight, stay there until he charges at you. As soon as he is VERY near you, move out of the way and watch him fall >
Non-Lethal way to get back at him:
Simply get a hammer and throw/impale it at his ballsack when he is sleeping.
Non-Lethal way to get back at him #2:
As soon as he is out of the house/dorm, LOCK HIM OUT. And then close ALL the windows and blockade the door with something, but first use nails and wood to advance lock it
Note when going outside: Look 10 ways before crossing OR go out the window and then look 10 ways before crossing 3 times.
Non-Lethal way to get back at him #3:
Invite all the friends you know to a house/dorm party and as soon as the party is over, tell all your best, loyal, and strong friends to tackle him, hold him down, and then slap/punch him silly xD