also used as an expression (by the idiots in mississauga) of surprise and unexpectancy.
sam: "YO! thats SEEN."
ian: "yo go play risk in my basement later, seen?"
*kristina spikes the ball and scores the winning point in the volleyball game against woodland*
tim: SEEEN! *jaw drops*
Or is just as often used as a question (instead of "know what I'm saying?" or "know what I mean?")
"true, true -- yeah man --seen."