Want to piss-off your roommate?
Simple....
PISS ON YOUR ROOMMATE!!!
Just a thought.
Or: Go to a pool supply store, buy a half-gallon (or gallon, if you're feeling particularly vengeful) of Muriatic acid. Get a large mixing bowl and pour equal parts Muriatic Acid and Bleach into the bowl...then get the hell out of there!!!! When the two combine, it creates a dense fog
which smells awful! The smell will linger for
weeks and she won't know what caused it - as the two dissipate if mixed in equal portions.
When you know she's gonna' be the only one using the bathroom, find some excuse and go Saran-wrap the toilet bowl! That'll make one hell of a mess....
Report her credit cards as stolen. All you need is the name of the bank which issued them, and then call the toll-free directory (if you're in the U.S., it's 800-555-1212) and get the number for their Customer Service division. Tell them you're her, and that your wallet was stolen. No, you don't have your account number with you, and no, you don't remember your Social Security number or anything else...you're too shaken up by the mugging. To be on the safe side, they'll close her accounts, and it'll be
maddening when she tries to use one and it comes up
Hold: Stolen Card at the store!!!!! BWAHAHAHAHAHAHAHA!!!
Call the IRS from a pay phone and tell them that she's been cheating on her taxes for the past 3 years....refuse to give your name, as you wish to remain anonymous - they'll audit her. It takes time, but it's probably the most vicious of the ideas I gave you....since they'll also keep an eye on her
future returns for the next 5 years!