There used to be a female human mage in World of Warcraft played by a 9 year old angry asian kid called "Odoylerulz".
On xbl, there was a guy called SHUTUPWIGGA, FARKANELL and FOTHERMUCKER.
The best was a 14 year old kid in CoD4 called XxXbANGASSasinxXX with the motto 'the pimpin just dont stop'. We called him ass banger for about a year and every time we beat him, our entire team would shout bang everytime he talked crap (all the time). Occasionally, we'd have a great conversation about how we really want it to, but that pimping just dont stop. Because it just dont.