Parents Music Resource Center
"The background history of the Parents Music Resource Center, or PMRC, would take up more space than it's worth to spell out in detail. There are several 'historical accounts' from which to choose. Let's arbitrarily choose this one:
One day in 1985, Tipper Gore, wife of the Democratic Senator from Tennessee, bought her eight- year-old daughter a copy of the soundtrack album to Prince's Purple Rain -- an R-rated film which had already generated considerable controversy for its sexual content. For some reason, however, she was shocked when their daughter pointed out a reference to masturbation in a song called "Darling Nikki." Tipper rounded up a bunch of her Washington housewife friends, most of whom happened to be married to influential members of the U.S. Senate, and founded the PMRC."
So in 1985, Zappa joined fellow musicians John Denver and Dee Snider in testifying before the U.S. Senate Committee on Commerce, Science, and Transportation against a proposed record rating system (similar to the movie rating system).