Switch the sheets on your beds while s/he is at class.
Twitch a lot.
Pretend to talk while pretending to be asleep.
Steal a fishtank. Fill it with beer and dump sardines in it. Talk to them.
Become a subgenius.
Inject his/her twinkies with a mixture of Dexatrim and MSG.
Learn to levitate. While your roommate is looking away, float up out of your seat. When s/he turns to look, fall back down and grin.
Speak in tongues.
Move you roommate's personal effects around. Start subtlely. Gradually work up to big things, and eventually glue everything s/he owns to the ceiling.
Walk and talk backwards.
Spend all your money on Jolt Cola. Drink it all. Stack the cans in the middle of your room. Number them.
Spend all your money on Transformers. Play with them at night. If your roommate says anything, tell him/her with a straight face, "They're more than meets the eye."
Recite entire movie scripts (e.g. "The Road Warrior," "Repo Man," Casablanca,") almost inaudibly.
Kill roaches with a monkey wrench while playing Wagnerian arias on a kazoo. If your roommate complains, explain that it is for your performance art class (or hit him/her with the wrench).
Collect all your urine in a small jug.
Chain yourself to your roommate's bed. Get him/her to bring you food.
Get a computer. Leave it on when you are not using it. Turn it off when you are.
Ask your roommate if your family can move in "just for a couple of weeks."
Fake a heart attack. When your roommate gets the paramedics to come, pretend nothing happened.
Eat glass.
Smoke ballpoint pens.
Smile. All the time.
Burn all your waste paper while eying your roommate suspiciously.
Hide a bunch of potato chips and Ho Hos in the bottom of a trash can. When you get hungry, root around in the trash. Find the food, and eat it. If your roommate empties the trash before you get hungry, demand that s/he reimburse you.
Leave a declaration of war on your roommate's desk. Include a list of grievances.
Paste boogers on the windows in occult patterns.
Shoot rubber bands at your roommate while his/her back is turned, and then look away quickly.
Dye all your underwear lime green.
Spill a lot of beer on his/her bed. Swim.
Buy three loaves of stale bread. Grow mold in the closet.
Hide your underwear and socks in your roommate's closet. Accuse him/her of stealing it.
Remove your door. Ship it to your roommate's parents (postage due).
Pray to Azazoth or Zoroaster. Sacrifice something nasty.
Whenever your roommate walks in, wait one minute and then stand up. Announce that you are going to take a shower. Do so. Keep this up for three weeks.
Array thirteen toothbrushes of different colors on your dresser. Refuse to discuss them.
Paint your half of the room black. Or paisley.
Whenever he/she is about to fall asleep, ask questions that start with "Didja ever wonder why...." Be creative.
Shave one eyebrow.
Put your mattress underneath your bed. Sleep down under there and pile your dirty clothes on the empty bedframe. If your roommate comments, mutter "Gotta save space," twenty times while twitching violently.
Put horseradish in your shoes.
Shelve all your books with the spines facing the wall. Complain loudly that you can never find the book that you want.
Always flush the toilet three times.
Subsist entirely on pickles for a week. Vomit often.
Buy a copy of Frankie Yankovic's "Pennsylvania Polka," and play it at least 6 hours a day. If your roommate complains, explain that it's an assignment for your primitive cultures class.
Give him/her an allowance.
Listen to radio static.
Open your window shades before you go to sleep each night. Close them as soon as you wake up.
Speak into a walkie-talkie in trucker's terms.
Divide the floor into an 8 X 8 grid. Arrange piles of laundry, books, pizza boxes, etc. on the glid and tell your roommate that you've turned the room into a chess game and not to move any of the piles.
Cover one of the walls with polaroids of fire hydrants from all over the city. Tell your roommate that you think that you were a dog in a former life. Stare lovingly at the photos, and make frequent trips to the bathroom.
Get a small, battery-operated clock which ticks very loudly. Put it in a briefcase and put the briefcase next to your roommate's bed.
Expound upon the importance of good personal hygiene. Wear rubber gloves and a surgical mask in the room.
Eat an entire bag of cheese curls at once. When you are finished, see how many times you can make orange fingerprints from all of the cheese junk left on your fingers.
Come home from class with a bucket of plaster of paris. Paint a section of the ceiling with it, and plaster your roommate's underwear to the stuff. When your roommate comes in and comments, tell him/her, "Sorry, I was doing your laundry, and I sneezed."
Wear the most obnoxious orange hat that you can find. Convince your roommate and everybody else that if they do not wear an orange hat, they will be hit by stray bullets.
Point west at 3 AM every night and yell, "It came from that way."
Walk around in circles all the time. Complain that your turn signal is stuck.
Whenever your roommate is out, turn the volume on his stereo ALL THE WAY UP. When he turns on his stereo, complain hysterically about the noise and his lack of courtesy.