People who think they're better than anyone else for any reason, pisses me off to no end.
If you have a problem with someone younger than you, remember that you were that age once too.
If you look down on how someone acts in a certain situation, you better be perfect in everything else you do.
If you refuse to talk to or interact with someone just because they're different from you in any way, you disgust me.
"Hah, she's just a dumb blonde"
"He doesn't have a girlfriend, he must be gay"
"She doesn't dress like us, she must be lesbian"
"Oh shit, that black guy is probably going to rape me"
"Avoid that Arab, he's probably got a bomb"
"That homeless guy stinks, what a waste of space"
This is why there is racism and why it will never be solved, because people look at what they see and judge based on stereotypes.