I just saw the stupidest—and funniest—sex film of the decade. John Waters made A Dirty Shame in 2004. Perhaps you’ve seen one of his 11 other films—Hairspray (made into a Tony-winning Broadway musical in 2003), the brilliant Cecil B. Demented, Pink Flamingos (one of 6 that he made with the cross-dressing, 300-pound actor Divine), or his first, Mondo Trasho (best movie title of the century, no?). A Dirty Shame stars Tracy Ullman, our era’s classic comedienne (think Claudette Colbert, Myrna Loy, Lucille Ball, Rosalind Russell) and pop singer Chris Isaak (our era’s um, Chris Isaak) as Sylvia & Vaughn Stickles,…