27.

Women in public restrooms who pee with such force it sounds like they're in there playing California firefighter. I don't know why this ... uh ... pisses me off so much, but it really drives me crazy. I don't need to hear that. If you're within range for normal human urethral diameter and aren't pregnant (or in some other way diseased) I shouldn't feel like I need to duck and cover when you whiz.

Also, the lady at work who grunts/groans when she sits down on or stands up from the toilet seat. Wtf is wrong with you?