Ungrateful/unthankful people:
These people just need to shut the forget up. Most of the stuff they say they go through isn't even that bad, and they won't stop complaining. Yeah, some people have been through worse, or don't have as much stuff as you, but they deal with it.
Backstabbers/users:
Sure, you may have helped someone with whatever the hell they're doing and may have been nice to them and all, but they don't care. They'll just do whatever they can with you to only help themselves, or use you until they get a chance at something better, and leave you with nothing.
Self-righteous/extremely hypocritical people/egofreaks:
You're not always right, there's no need to start a terribly put together argument to defend your idiotic position in hopes to increase/save your reputation for whatever, and when these types of people start to get desperate, they usually spew out stuff that contradicts what they first said, and when you point that out to them, some mini-argument branches off of the main one as they try to prove you wrong when you are obviously not.
All of the above in one:
I used to be friends with some guy who matches all of the above descriptions. He wasn't like this at first, but by 8th grade he was a straight-up wigger forgethead who apparently thought I should do whatever he says or he'll beat the stuff out of me because he's apparently stronger and a better fighter. He pisses me off to the near max as of today, but every time he tries to get in a fight with me, he finds a stuffty excuse not to, so I have nothing to get rid of my anger but a brick wall to punch, which really really hurts once my anger goes away D:
The moms who put their kids in beauty pageants:
They need to be shot
2. People just standing there in the hallway and not moving when I'm trying to get to my class.
Plow through, it's as fun as hell