A combination of shit-faced and wasted; that is to say, extremely drunk.
May or may not lend a more German-sounding twist to the word, as in "Let's get shfasted, ya!"
Also gives the impression that one is already drunk, seeing as how saying the word requires some slurring of syllables. This is the irony of "shfasted."
Kelly: "I can't wait for this party!!!! I'm going to get totally shfasteddddd!!!"
Joe: "I think you already are..."