A post on the official boards lead me to do the same here on Alla.
List what you consider to be the most annoying mob in the game, and your reasons why.
My pick has to be murlocs. Not only are they utterly annoying sounding, but they like to link with each other a mile away and spawn right on top of you when you are resting from battles.
PS: Please ignore this topic if you don't like it. No need to ninja-ratedown.