I hate it when somebody is horribly mistaken over a simple thing that should be general knowledge or at least able to be determined with thought (CONIFERS are the softwoods, HARDWOODS are, well, the hardwoods. Dumbass.) but will argue with you incessantly on it anyways, and not be able to be convinced of simple facts no matter how many ways you say it (Politics and opinions don't count. SIMPLE things.)
I hate punks who try to pick fights with me for incredibly stupid reasons. Also the phrase "you wanna dance?", even when used in that context, still sounds really gay.
I hate it when people can never make up their minds, or when they can never change them as well.
I hate when there is uncertainty over a really big, potentially devastating issue. Either it's there or its not, I can handle that somehow. Perhaps-it-might-be-but-wait-maybe-its-not-although it-could-be uncertainty drives me nuts. Ugh.