Frank Zappa fans of the lounge - what would you consider his definitive masterwork?

For those who may not know the whole story behind the album, let me fill you in. Zappa originally conceived Lather as a 4-record box set. FZ's record company at the time (Discreet - a now defunct subsidiary of Warner Brothers), didn't want to release it. Zappa then tried to release it with another record company (Polygram) as a 'special project'. Polygram briefly agreed to release the box set, then reneged on the deal, due to legal complications with Discreet.

Discreet told Zappa that he owed them four more records under his present contract. In an attempt to fulfill his contractual obligation, Zappa reformatted Lather and delivered the remaining four albums all at once. They wouldn't pay him, nor would they release him from his contract. Never one to be pushed around by the record labels, Zappa took Lather to a local radio station in December of 1977 and asked them to play the entire thing. Frank assumed the role of "temporary bogus disc jockey" for this special broadcast. After asking listeners to get their tape decks set up, he delivered Lather to the radio audience for free.

Soon after the radio broadcast, Lather saw it's first release as a bootleg 4LP box set. There was also a double-LP bootleg called Leatherette. It featured songs from Lather, plus tracks alleged to be from the same sessions (including the still-unreleased studio version of "Dead Girls of London" with Van Morrison on vocals). Commercially, the material ended up being spread out over a number of albums. The final four Zappa releases on Discreet all had tracks from Lather, as did the excellent Shut Up and Play Your Guitar series. Sheik Yerbouti and Tinseltown Rebellion both featured cuts as well.

http://www.thenightowl.com/reviews/fzlather.htm