An Austrian-accented slang version of the word "stuff," as in random things, now incorporated into American slang probably through characters like Hans and Frans from
Saturday Night live who were a spoof on Austrian-American bodybuilder/actor/film-maker
Arnold Schwarzenegger.
It is often (but not always) emotionally loaded, as in "stuff with
emotional baggage attached."
"He needed to talk about his schtuff, so now he's seeing the psychoanalyst
down the street, Dr. Schwarzenfreud."
"She has a lot of schtuff goin' on in her life right now. Give 'er a break."
"Dude,
that's a lot of schtuff in your garage! You need to
feng shui the sh*t out of that!