Common mistyping of "owned" (because the "p" key is next to "o" on a keyboard). To dominate in a multiplayer game, or to be very very good in some other way ("Metallica pwned at Monsters Of Rock")
Used by lamers who think its cool to act like a retard and forget that O and P are 2 different keys.
All the fags arguing are depressed because their dad pwned them in the back of the head for masturbating too much. This is why they can't spell owned, nor can they laugh without saying LOL!