Noob

A name given to a person who is very bad at what he is doing. Often mistaken as the same as newbie or newb, but a noob is someone who is as bad as if they were a newbie. Commonly used in video games, such as World of Warcraft, Counter-Strike, Halo, etc.
There are many variations of the name in, for example in leetspeak n00b, and nab, nub, plus many more.

Cole: Man, I was playing Counter-Strike for 8 hours last night! My best score was 15-134!
Andrew: sigh... noob...