People who go out of their way to be an arse. Seriously, it's annoying. It's not cool, it doesn't make you tough or anything. It makes you annoying.
In general, it irks me when people act like they are better than everyone else, for whatever reason. Though it can also be irritating when you're stuck as the ONLY person working on something when it's supposed to be a group project 'cause the others are all talking about crap that's supposed to make them look badass.
Oh, and anyone who takes things to the extreme. I hate it when people do that, because it makes them so blind to everything else. Especially when they're so absorbed in their belief that they can't take any opinion that does not match their own.
There are others, but I can't really think of them at the mo'.
EDIT: Whiny people who don't do anything except angst about their lives and how horrible it is. And probably make up about half of the stuff just for attention to boot.
THAT EXPLAINS HIS DISAPPEARANCE! THE COPS GOT HIM! THE PSYCHO WANKER OF WANKING TOWN!
meet me at cafe nero quin mate we'll get something syrupy and laugh off the pain yea