Mind you he/she was spamming the chat room (hmm, looks like toilet mouth, insults, and ad links :) ) instead of paying attention to the nub he was fighting.
nublet: <censored> <censored> <censored> <censored>!!!!
NUBLET has DIED!!! 1 exp earned!
nub: haha u got pwned! but im still a nub ;(
Word came from nub which came from noob which came from newb which came from newbie. This word originated in IRC and got spread around via popular multiplayer games such as Counter-Strike