Ew, this one is big for me. Biting the fork/spoon, chewing with the mouth open, or even loudly chewing with closed mouth, breathing loudly while chewing...
For that matter, I can't stand the way it feels when someone breathes on me, either. Part of why it takes me so long to get comfortable in bed at night is because I have to make sure my arms are positioned so I'm not breathing on myself! (along with all of the other factors that must be considered, lol)
Another thing that annoys me to no end...aluminum foil. Ugh! I can't stand to touch it or hear it. If I have to touch it, my teeth hurt. It's worse if I'm eating at the same time as touching it, or if it rubs against the rings on my fingers or touches my fingernails.
Along those lines, I have to keep my nails very short. If they're too long, it annoys me for them to click against the keys on the keyboard when I type (I'm on the computer a lot for work). I also can't stand for my toenails to get long, because one will start digging into the toe next it, and that just about gives me a panic attack, lol.