People who are shitty to cyclists. Yea, it's because I can't AFFORD a car. You want to buy me one so I can commute by that rather than a complicated network of bike trails (Currently having to bike 23 miles to get to class due to my current living situation), then be my goddamn guest. Just pass me. You're not making any point by yelling at me, staying 2 feet behind me, and throwing your garbage at me, other than that you're an ass. Usually, the hostility of the jerk in question increases with how fat they are and how much gas their model of car uses. Wonder why.
Okay, that's just my soapbox rant for the day because I encountered one of those morons during my commute today.
Really, I think the worst people are pessimists. The ones who wallow in self-pity and want to drag everyone down with them, and they live in a constant state of anger at things they don't like. They're annoying and probably not healthy to be around.