<Puts on flame retardant suit>
My biggest one is the people at my job who stand around yapping in Spanish (they all speak fluent English as well) to each other so they can talk about co-workers etc. I know bits of Spanish and I've picked up parts of their conversations because they are SO LOUD. First of all, they all live in very Spanish neighborhoods. This is not their only means to speak in their native tongue. Second, they do it specifically to be exclusive, instead of striving for the all inclusive type workplace everyone else wants. There are like 4 women in my dept. (in an office) who do this. They do it all the time. It aggravates the heck out of me , and most of my other co-workers. Unfortunately, nothing can be done to stop them.
People who talk in hip hop slang too. Esp.. if they are doing so in a workplace.
My next one is pretentiousness. People who won't listen to a top 40 song, see a popular movie and even one who won't go to WDW because it's not "trendy and underground". These people also tend to only call movies "films". I don't know why but it irks me.
I can't stand people who are blinded by political ideology either on either end of the spectrum. And people who constantly whine about their "horrible lives, bad relationships etc." but refuse to take steps to better themselves.
Oh - and when I see young girls dressed like prostitutes....do their moms let them out of the house dressed like that?!?
Grrrrr.

But there are also a lot of things I love about people. Polite people, friendly people, honest people etc. I probably sound like a curmudgeon. But I'm not I swear!