People who chew gum (or anything really) with their mouths open, argh! Seriously people, it's annoying, chew with your mouths closed!
Also, people who constantly spit in public, made even worse if they make the awful hacking noise first. Okay, I understand sometimes you might get phlegm stuck in your throat, but that's why I carry tissues everywhere; if I get phlegm, I'll spit into the tissue so that everyone doesn't have to see it. But sometimes people just... SPIT OVER AND OVER FOR WHAT SEEMS LIKE NO REASON! It's disgusting! It's like, someone will spit, wait like, 20 seconds, spit again, repeat, over and over! What's even worse is when people spit INDOORS! It happened in GameStop today. GameStop! I was looking through the bargain bins while some guy like, 3 feet away at the Wii games made that HOOOOICKKKK noise and spit right there, on the floor... And then he did it again at least 3 more times before leaving the store! Oh my goodness people, have some class, PLEASE!