It's an act of totally whooping someone's ass in wii sports for the wii. More specifically doing it with your own mii and getting the satisifaction that the fact that you have no life and have no chance at getting a girlfriend has finally paid off in some form.
Player 1: Damn you beat me good... and wih your own mii
Player 2: Damn right son! You just got mii'd!
Player 2: Damn right son! You just got mii'd!
by random_knowledge June 15, 2007