Print a fake parking ticket that “came in the mail”. This is all you need to make it convincing! Get hundreds of plastic cups, fill them with water, and place them closely together (3cm apart) all over the room (floor, desk, window sill, etc. ) 4. Put mentos in the ice tray. For a pair of roommates, switch all or their possesions. Tape together a bunch of sheets of newspaper to cover the victim's doorframe. Then tape a big sheet over the doorframe and leave a gap of about two or three inches between the sheet and the door. Fill the gap with paper balls right to the top of the doorway. First, remove the shower head and inside the shower head you can put peppermints. So when your roommate takes a shower, the peppermints will dissolve and the residue will go through the shower head with the water.