Everyone can identify the obvious causes of roommate strife. You're a slob. You're a mooch. You invite unsavory characters back to the communal pad.

But many students hate their roommates for stickier, subtler reasons. Some of these reasons are your fault. Some are beyond your control. Either way, knowing why you're hated is half the battle. The other half of the battle involves secretly tampering with their stuff... (I'm just kidding. I don't endorse tampering. Please don't write angry comments, or in any way corrupt your roommate's Captain Crunch.) And feel free to add your own comments on why some roommates can't help hating each other.

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 Although it’s the most common source of tension among female roommates, this reason rarely if ever comes to light, as women are adept at obscuring insecurities behind self-righteous rationales. For example, they’ll say they think it’s morally wrong that you’re dating more than one person. They think it’s academically irresponsible to always ask for (and receive) assignment extensions from your male professors. They find your Halloween costume –- a Lady Gaga-esque take on Red Riding Hood -- degrading to women. They will wage a war of mini-battles, from eye rolls to passive aggressive Post-It notes in common areas (were you expecting one of your MANY boyfriends to empty this waste basket?), until someone prettier than you or uglier than them transfers into your townhouse.