I'm pretty sure you can call people in the real world "noobs" but I could be wrong, let me check.
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OK so I called myself a noob in the mirror, then promptly retorted to my mirrored self that no, you're a noob. I went downhill from that, with me coming up with greater and greater insults for the mirrored person until it erupted in to a fist fight. At first the fight was remarkable even, with me and the mirror trading perfectly matched blows, but after a time the mirror broke and I pronounced myself the winner.
So: you can call people noob and it is insulting, also, mirrors are good boxers.