I only can't stand children, or little kids around the Internet. First, they think they are the best or the hottest stuff in the world, second, they don't care for the others; they'll only be for their own benefit, as you'd call your common hypocrite, and finally, they are extremely annoying when it comes to serious conversations.
But it's natural. You can't ask a kid to behave. When something really perturvating happens in their lives, they'll grow up. Oh, and of course, what pisses me most are adults who act as children. Deceptionating. (Don't get me wrong, please, I'm reffering to behaving like an annoying person that doesn't even respect you).