The Daily Grind: What behaviors get your goat?

There are people who you don't like in any MMO, and that's more or less a given. But sometimes even the people you like can drive you into a paroxysm of rage. You could have known someone in the game for years, rely on them implicitly, and yet always feel that tickle of rage when they start slowing down in order to loot things in the middle of combat. (Or if you're playing City of Heroes and they stop mid-fight to tinker with their Enhancements, which is even worse.)

The problem is that these sorts of behaviors aren't bad things by themselves -- none of them have a major impact on gameplay, and they're not large enough to force an argument or discussion. But they irritate you, even though they're not a big deal, and you can't help but notice them. What sort of stupid human tricks bother you when you're playing? People looting in combat? Not mentioning when they need a quick break to recharge? Talking too much or too little? Let us know!