1. Whining about things that are good: These things include but are not limited to whining about travel (ughhh I'm never home! I was just in Europe for two weeks and now I have to go to Asia), over-commitment with things that are awesome (oh fuck, I have an audition and a rehearsal and a callback AND another rehearsal and a staged reading), and why having a boyfriend isn't as good as being single (he bought me dinner AGAIN and all I wanted to do was stay home!). This might actually be my biggest pet peeve at present.
2. People who are not poor who say they are: If you ever openly admit in my presence that you a) don't have a job, b) aren't looking for a job, and c) intend to live off of mommy and daddy's money for as long as humanly possible without contributing at all because you for ANY reason feel that they owe you after the age of 22, the next time I say let's go to dinner if you say you can't because you're broke/it's expensive, I'M GOING TO STAB YOU. I have three jobs and I'm still way below the poverty line. Shut the fuck up, tell your parents thank you, and don't talk to me until you learn ANYTHING about the value of money.
3. Reading over my shoulder: A simple classic. Please. It gives me the heebie jeebies. I admit that I have an unreasonably high personal space boundary, but really. Just ask - I'll give you the book/magazine/newspaper or turn my computer your way.
4. Poor grammar: Another simple classic. Your and you're? Not the same. Ditto there, their, and they're. See again it's and its. Don't get me started on comma usage or incorrect plurality.
5. Being asked why I don't have a boyfriend: Dear men everywhere - asking me why I don't have a boyfriend in that bewildered, "you're so great" way is not flattering, it's annoying. It does NOT make me want to smile demurely or laugh or bat my eyelashes or flirt. It makes me want to say "I don't fucking know, so you'd better tell me what it is about me that strikes you as undateable" and then stalk away in my most enraged but still appealing way. This goes double if you and I have ever engaged in any sort of... flirtation and triple if we've ever actually dated but you're curious as to why I'm still single now.
[6. Honorable mention -the word moist. Seriously, my hatred of this word is so well known that people will say "that word you don't like" rather than say moist in my presence.]