Noob read upside down(see the definition for noob for more inquiry). Usually typed to confuse the opponent for a moment and display even more of their stupidity
On Facebook
Brad's status: Oh yea I just got another trophy on Cod!
Matt's comment: You're such a qoou, i got platinum ages ago
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi