My top three (in no particular order):
Chewing
The sound people make with their mouth when they just sort of half open their mouth and then close it again a few times.
Loud kissing. As in, when two people just do a normal kiss, but manage to make it REALLY loud. It's so annoying.
Others:
Slurping
Loud typing
Snoring
Overly loud breathing / siging.
Children that are crying because they aren't having their way.
The sound of a girl talking really stupidly, as in she makes the words reall long and end every sentece as if it's a question.
So, Flood. I want you to look deep in to your grumpy side and think of what noises irritate the crap out of you.
[Edited on 12.06.2012 11:41 AM PST]