It means for real, it is a part of the izzle dailect, in which you take the first letter and add izzle, in which most are like this. In this case making for into fa and adding sh and then izzle.
It may also be said foshizzle, forshizzle or fashizzle, never is it forizzle.
you must of just got owned by Fashizzle Sizle in a game of halo causing mass amounts of pain and agony as he valiently t bags your body into the ground.