The term used describing someone who fails hard at a game the he/she has lots of experience with. The term is becoming so popular that in no longer applies to just games anymore, but applies to everyday lifestyles. Its also very common for a person to mistake noob and newb as the same meaning. Newb simply means someone who is new to something, able to catch on at normal speeds, but is just unfamiliar.
Guy 1: That Tom is taking a long time to learn how to drive stick
Guy 2: Yeah, what a noob
Boss: Peter, you've been working here for a month, and you still havent learned the materials or the procedures. You're not a noob are you?
Gamer 1: WTF! This guys hacking, he keeps killing me so easily
Gamer 2: No, your just a noob who fails hard