Stuff I've done this year to people in my dorm...... Some you might not want to do since you live in the same place:
-Shit in a cup and hid it in their room where they wouldnt find it.
-filled a condom with about 5 gallons of water(just to breaking point), then me and someone else carefully carried it on cardboard to the person's room and set it on their bed then slid the cardboard out. As soon as he tried to pick it up, the condom burst and water went everywhere.
-fill shoes with baking soda
-took an accordian folder and filled it with shaving cream then slid the open end under the door and stomped on it.
-the leaner, filled trashcan with water and leaned it on person's door then knocked
-penny locked, shove pennies and dimes tightly into shut door around the handle putting so much pressure on the door he can't turn the handle
-pissed in a plate, froze it turned the plate upside down and slid the piss disk under the door
-the whole shaving creak smack into their face when they're sleeping
.....i know I've done more, when I think of it I'll post them