we're just putting saran wrap across their doorway, and taping it to the walls, so there's just a clear wall when they open their door, and a note declaring war on them.
the shaving cream is the awesome one.
You take a manilla folder (the kind with sides) fill it up with shaving cream, slide the opening under the victim's door, and stomp on the full part, thus spraying shaving cream ALL OVER EVERYTHING IN THEIR ROOM.