It is common knowledge it originated in warcraft; you'll see a lot of those here, so I wont bore you by repeating it. However, it also applies to when people get lots of thumbs down for their bullshit definitions of "pwned"
The true origion of pwned was in Counter Strike.. it is not a mispelled 'owned' it formed when an opposing player was killed with a pistol instead of a main gun
so they would be pistol owned or pwned..
Pwned is a word that was most likely created by a noob on a video game that typed "pwned" instead of "owned."
It has become used by non-noobs, perhaps to make fun of the person that made it, perhaps because it is so lacking in proofreading, it is hilarious.
lykomg u got pwned dood - noob usage
Haha, that teacher totally pwned you, man. - Everyday usage