I found these on google. Some I want to try and others are kinda messed up. These are some of my favorites.
Move everything to one side of the room. Ask your roommate if he knows how much an elephant weighs, and look at the floor on the empty side of the room with concern.
Create an army of animal crackers. Put them through basic training. Set up little checkpoints around the room. Tell your roommate that the camel spotted him/her in a restricted area and said not to do it again. Ask your roommate to apologize to the camel.
While your roommate is out, glue your shoes to the ceiling. When your roommate walks in, sit on the floor, hold your head, and moan.
When you leave the room, put on a screensaver that says, "I'm watching you."
Tell your roommate, "I've got an important message for you." Then pretend to faint. When you recover, say you can't remember what the message was. Later on, say, "Oh, yeah, I remember!" Pretend to faint again. Keep this up for several weeks.