fizz is another word for someone who is addicted to something. another word for "fiend".
Ex. 1
Guy 1 : I really need a cigarette right now so bad, I am shaking.
Guy 2: Damn you be fizzing for cigs like that?
Ex. 2
Guy 1: Is Bob blowing up your phone right now?
Guy 2: Yea he's fizzing for some coke right now but nobody got it.