Girls who post their user pic as a picture of their boobs or them making out with their boyfriends. It's gross, no one wants to see that unless their at mardi gras. And even then, no one really wants to see it.
Boys whom I have never met sending me inappropriate pictures. I don't want to see it either.
People who obsessively add friends to their myspace or facebook pages No one is freinds with 60,000+ people in real life. You don't have that many frinds, get over it.
People who use u for you ttyl for talk to you later, etc. It's not that hard to write out the word.
Boys who honeslty believe I will meet them for sex in the real world, after knowing them for 2 seconds online. That's weird, I'm not a prostitute and those guys usualy look like they need to pay for sex. I myself, don't.
People who only write abou thow much they love their "Shnooky Wooky", i.e their significnt other and how great their relationship is. If it were really that great you wouldn't need to be reminded every three seconds.