noun - derived from the verb: to own
Definition: The state of owning or being owned by another individual in an activity, sport, video game, insult, comeback, or other similar achievement.
United won 3-0. Ownage!
You got another 2000 points in that game. Man, that was total ownage!
NB. Alternative spellings:
(I have this on good authority from a 14 year old.)