Ok I have a couple, first one is if you have a sink with a sprayer on it, use electrical tape to lock it on and aim it so it soaks the person who turns on the faucet. second one is to remove the keys from the keyboard and replace them in whatever order you want.. the BEST one I dont know how you will do it because it has to be a sealed room, with a door which opens inward and the person has to be in it. great for dorm room pranks or if the person is inside sleeping (or if your quiet) heres the steps.
---when the victim is in the room and you know the above criteria apply,
1)Seran wrap the outer edges of the door.
2)start at the bottom with seran wrap and go from side to side of the door frame making a pocket between the door and seran wrap.
3)continue working your way up until you get to about the top 1' of the door.
4)take styrofoam bean bag fill and pour it into the pocket you created.
5)finish filling to the top of the door and seran wrap the top making it an air tight pocket.
YOUR DONE!! when the victim opens the door it creates a vacume and the bean bag fill explodes into the room and gets into EVERYTHING!! worked great when I was living in the dorms.
