• Claim you were a Christmas tree in your former life. If s/he tries to bring one into the room, scream bloody murder and thrash on the floor.
• Go to the mall with your roommate and sit on Santa's lap. Refuse to get off.
• Wear a Santa suit all the time. Deny you're wearing it.
• Sit in a corner in the fetal position rocking back and forth chanting, "Santa Claus is coming to town, Santa Claus is coming to town..."
• Hang mistletoe in the doorway. When your roommate enters or leaves the room, plant a wet one on his/her lips.
• Hang a stocking with your roommates name on it. Collect coal and sharp objects in it. If s/he asks, say, "You've been very naughty this year."
• Paint your nose red and wear antlers. Constantly complain about how you never get to join in on the reindeer games.
• Make conversation out of Christmas Carols. (ie, "You know, I saw mommy kissing Santa Claus underneath the mistletoe last night.")
• Wrap yourself in Christmas lights and roll around in the snow.
• Sing: "All I want for Christmas is my roommate's two front teeth..."
• Give your roommate the gifts from the twelve days of Christmas song.
• Build a snow person with your roommate and place a hat on its head. When it doesn't come to life, cry hysterically: "It didn't work!"
• Whip your roommate screaming: "Now Dasher, now Dancer, now Donner, and Blitzen, etc."
• Tear down all your roommate's Christmas decorations yelling, "Bah Humbug!"
• Wake up every morning screaming, "Ghost of Christmas Future, please have mercy on my soul!"
• Tell your roommate you're moving out. Santa's buying you a house on 34th Street.
• Pin a poinsettia to your lapel.
• Make anatomically correct gingerbread people and eat the best parts first.
• Put on a fake white beard and insist that all your roommate's friends, "Give it a yank."
• Ring jingle bells maniacally saying "every time a bell rings an angel gets his wings."
• Stand in front of the mirror in your underwear reciting, "How the Grinch Stole Christmas" over and over.
• Smoke mistletoe. Do what comes naturally.
• Watch your roommate when s/he is sleeping. When s/he wakes up, sing, "He sees you when you're sleeping..."
• Steal a life size nativity scene and display it in your room. When your roommate asks, tell him/her, "I had to let them stay here, there's no room at the inn."
• When your roommate goes to the bathroom, rearrange his/her possessions. Tell him/her that Santa's elves must have done it.
• Take some miniature marshmallows and put them in a little baggie. Attach a note to the bag that has a picture of a snow man and this poem:
  'You have been naughty, and here's the scoop:
  All you get is the snowman's poop!'
  Or you could have a picture of a reindeer with cocoa puffs for reindeer poop for your roommate.