People who are just... stupid (There was this guy in my history class last year who proposed bombing Mecca as the solution to terrorism today. I almost strangled him)
Ketchup- I'm not sure why, but I find it absolutely repulsive. All red... and gooey...*shudder*
People who refuse to admit their mistakes, particularly teachers (My 6th grade teacher, after I had proved that I was right and that she had misled the class, refused to give the points she had unfairly taken off because I "hadn't followed what she taught")
Teachers who don't teach.
Teachers who grade inconsistently/unfairly/don't explain their markings.
People who, during an argument, refuse to recognize that you have outmanuevered them and simply reiterate the same nonsensical points over and over.
People who are amazing at absolutely everything.
People who suck up to teachers (and, conversely, teachers who pick favorites).
Parent who nag.
Parents who refuse to accept your independence.
People who are touchy (I'm not actually particularly touchy, despite what it may seem from my list

)
Jocks who take pleasure in ridiculing shy girls who are only minding their own business.
Asymmetricity (It's actually gotten better-I used to be really obsessive about it
There's probably more, but...