To be, or think you are, the best person usually on such common online games such as Halo 3, Call Of Duty 4, and other online shooters. Teh Pwnz (the pwn) is spelled wrong on purpose, such as 1337, and is most used for bragging.
Spectator: Whoa, dude, that was a good kill!
Player: I know, since i am teh pwnz i do that all the time!