It was deemed necessary to have a euphemism named after Wolfgang Amadeus Mozart, due to his rock-star-like behavior in [the movie Amadeus]. The youth culture of Chicago started using this euphemism as a sign of respect for the somewhat timid or classy music (which was revolutionary in its time) and the juxtaposition of a wild and carnal celebrity.Which is all nonsense, Tate says in this interview. "I made up all the histories. Every word of it. There was no scholarship. You can't really prove where a euphemism came from. I used whatever I felt was most plausible, and some of the true facts really came together in a way I appreciated."
I haven't read Tate's book, but my taste runs to actual etymologies, not half-baked stereotypes of classical music. (Check out the Random House Historical Dictionary of American Slang for a book that does it right.) And while Tate claims that the euphemisms themselves are authentic, and only the histories are made up, "doing a Mozart" sounds suspiciously pat to me.
Besides, in Chicago, "Mozart" has another range of reference that's far less cute. No doubt due to the influx of German immigrants in the 1800s, Chicago has a whole row of streets named after German cultural heroes: Schiller, Goethe, Schubert, Mozart. And the intersection of Mozart Street (pronounced with a soft "z," by the way) and Augusta Boulevard, out by Humboldt Park, marks the center of territory controlled by the Insane Dragons street gang (who have their own web page—those Chicago gangs are organized). According to that page, Mozart and Augusta is known as the "Dragon's Pit," and the locale rates its own entry at UrbanDictionary.com. I'm hardly an expert on gangland Chicago, but even I knew that being out around Humboldt Park after dark was liable to leave your wig askew.