Fiz-Fucked is similar to fuck, but used to put emphasis on that particular saying. For example, if you were to say someone is fucked, and his friend is fiz-fucked, it is implied that the fiz-fucked one is more fucked than the person that is simply fucked.
Jonah: 'Hey, what time is it?' Jean-Luc: "Nearly 11:30." Jonah: "Dude, I'm fiz-fucked!"
Jean-Luc: "Yeah, so that guy runs in with the noob cannon, and I just knew I was totally fiz-fucked!"