Everyone's got that one thing they can't stand that other people do. Everyone's got a breaking point where if they see someone do THAT ONE THING just ONE MORE TIME, you'll be out the door faster than a baptist at Burning man. No matter what role you play, tank, healer, dps, whatever, there's that one thing you've had alls you can stands 'till you can't stands no more.

Mine is knockbacks. I like playing melee classes, and nothing is more annoying than some dude giving into this voice in head whispering Knock back all the things! Especially when they're trying to use it as a coup de grace on something that's almost dead. Like, what is the point? What are you doing, man? Just let us kill it! (Machinists, you are SUPER guilty of this!)

A close second are people who keep jumping everywhere. I dunno, it's just aggravating.