But I think it is important to direct you to my declaration of my biggest in-game pet peeve: "rogue" vs. "rouge." This misuse really, really bothers me. I understand that it is an easy typo, but I also believe that many people think that is how rogue is spelled. As I've said before, rouge is a cosmetic applied to your cheeks; rogue is a deadly killer who likes to make with the stabby. My common response to that is (stolen from someone else): Rouges are overpowdered. That statement often gets a mixed response from the chat audience -- many misread it and want to start a class war.
Another thing that makes me rather irritated is "ne" instead of "any" in any context or word form. It's only one letter shorter! It actually takes me longer to type "ne," because I naturally type "any" as a touch typist. I know some people can't stand "plz" as an abbreviation, but I don't mind it anymore. "Please" is a much longer word than "plz," and people like shortcuts. But one letter! Gah! I need to get over it though and take Allie Brosh's approach. Maybe everyone who does it really only has one finger on each hand. I should be more tolerant.
Now, if everyone but funsuckers severely dislikes a particular thing, I don't think that is a pet peeve. For example, someone's stealing your gathering node while you are clearly fighting the mobs protecting it is not a pet peeve -- it is righteous anger. A mammoth sitting on a vendor, quest giver, or mailbox is reportable -- not a minor annoyance (also a really good target for Baby Spice).
But someone's asking a question in guild chat that can easily be looked up on Wowhead annoys some people but not others. If I know the answer off the top of my head, I am happy to respond. Not everyone feels that way and will insist on directing that person to the appropriate online resource.
What things bother you in game that aren't necessarily universal dislikes? How angry do you get about them? Which pet peeve is the worst for you?