Most assuredly not a German word, as asserted by the douchebags previous to me. Shiza, literally, means nothing in German, as in - of course - that it holds no meaning. Saying "shiza" to a German person will warrant you an odd look, and possibly an insult.
(Dip shit) SHIZA! SHIZA!
(Reasonable person) Shut up, fucktard; that's not an actual word in any language, at least not in the context in which you use it.
(Dip shit) Yes it is! It's German!
(Reasonable Person) Sigh, there's no point in trying to persuade you.