A noob who in not only new to the game but is also defeating everybody there. xemt is usualy used normaly at the end of a game to praise the noob or to get angry with them.
o0 lighting 0o (xbox 360 gamertag): "that cremwhip geezer totaly xemt the game."
redfangnight (xbox 360 gamertag): "yea. if he is that good that he xemt us then we should invite him into our game gang"