~ Claim you were a Christmas tree in your former life. If s/he tries to bring one into the room, scream bloody murder.
~ Go to the mall with your roommate and sit on Santa's lap. Refuse to get off.
~ Paint your nose red and wear antlers. Constantly complain about how you never get to join in on the games.
~ Make conversation out of Christmas Carols. (e.g., "You know, I saw mommy kissing Santa Claus underneath the mistletoe last night.")
~ 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 snowperson with your roommate and place a hat on its head. When it doesn't come to life, cry hysterically, "It didn't work!"
~ Ring jingle bells maniacally saying, "Every time a bell rings an angel gets his wings!"