One glitch that annoys the crap out of me is when all the icons and chatbox start dissapearing, then reappearing rapidly. I have to play the Direct3D9 just to enjoy it not doing that, but after too long, Direct3D9 will start crashing. Its all my laptop's fault. I specifically say I want a computer that can handle my games, but instead I get one that cant even change the dang desktop background, unless you pay 300 bucks just to do it.
Another is related to the first one, which is when the head dissapears and you can see your character's eyes, teeth, and tongue.
Yet another is the LOL face glitch. If a friend keeps changing their face and stop suddenly, depending if their tongue was out, their mouth looks like their howling (only wider), and the tongue is completely out. They have to log out n back in just to fix it. XD
last, but not least, the map derps. I HATE when you download a map, and you cant see certain objects. Along with when friends download your maps, and they cant see certain objects. If thats not a gltich, then what the fluff is it?