probably my biggest thing is someone who eats snacks out of one of those noisy foil bags and insists on ramming their hand in and "feeling around" for 5 minutes to get a handfull, that noise will make me scream in seconds!
Oh yeah, and people who eat with their mouths open smacking their lips the whole time! That's one thing I will make a comment to someone about in a second ... I don't care who it is or where we are!
Lastly, people who are ALWAYS late! I pride myself in almost always being on time or early!