I hate hate HATE when people chew loudly. Really, people, how difficult is it to keep your mouth shut when you are eating. You have been eating solid food at least 3 times a day since you were approximately 1 years old, so by now you have had lots of practice. It baffles me that some people make horrifying and nauseating noises during eating and no one has thought to tell them. Not once in their entire life did some kind soul say, "Hey, I gag a little every time we eat together. Can you try to keep your mouth closed? Thanks."
There are exceptions, to this, of course: when you have a bad cold and you cannot breathe through your nose, I will give you a minor pass, but you should also try to avoid eating around people since you are sick and probably contagious.
I was tragically reminded of this, one of my most hated pet peeves, this morning on the T when I stood next to a 9 year old girl with a giant wad of gum in her wide open mouth. [Side Note: Yes, I recognize that I sound just like my father did when I was 9 and had a giant wad of gum in my wide open mouth and we were going on some kind of road trip but we all turn into our parents some day, I'm just embracing it early on.] I'm not sure why her mother didn't grab her and say, "HEY! You are chewing so loudly that this kind, patient, gorgeous lady next to you [read: me!] can hear you over her iPod. Spit out the gum!"
Probably the worst case of loud eating was one of my old roommates. I'll call her Ugly Face for lack of a better nickname. She used to eat frozen lasagna so loudly that I could hear her across the apartment. "How can you eat lasagna loudly," you might be wondering, "it's such a soft meal." Well, Ugly Face managed it, smacking her tongue around, chewing with her mouth open, and making all sorts of disgusting mushy noises.
So the next time you eat a meal with any other person, especially if it is me, try to be aware of the noises you make. If you can't seem to control your mouth's unfortunate soundtrack, don't be too insulted when I glare at you the entire meal.