Seriously. Here are some actions that annoy me in World of Warcraft:
-Level 60 UD Rogues killing lowbies like yours truly outside of Booty Bay and shit.
-Players who dont wait for the mana guys (like me, a Druid) to regain mana before attacking the next mob.
-Players who say they need shit "for their alt" from an instance.
-People who dont properly hold aggro.
-Level 21/31/41 non-Druids grabbing the flag in Warsong Gulch.
Now Im not gonna lie, Im not perfect and most of the WOW players are pretty solid and fair. Even the above doesnt drive me nuts - its annoying, but what can you do (though its not fair to accuse a healer of poor healing skills when the group cant hold aggro).
But one thing annoys me more than all of that. People who take the game so fucking seriously. Treat it like life or death. Bitch you out when you do something supposedly run. Ive grouped with at least two of these players and they were both miserable people and miserable experiences. 99.9999% of people play World of Warcraft to sit back, relax, and have fun, but its always those few...
Once I hit 60, though, I guess I dont have to play with dorks like that anymore. More motivation, I guess? But at the same time I got like another 16 levels of it.