A funny thing happened when stand-up comic Jon Stewart sat down to write a book: He actually wrote a funny one. Rather than merely transcribe his monologues (like Jerry Seinfeld did) or pen a confessional tell-all (like Roseanne did twice), Stewart's Naked Pictures of Famous People consists of 18 original humor pieces on a par with Woody Allen's Without Feathers and Steve Martin's Cruel Shoes.
As its title implies, Naked Pictures strips various celebrities bare. In ''Martha Stewart's Vagina,'' the domestic doyenne advises her readers on how to dress up their loins with ''vagina treatments'' (''For the summer you may want to go with simple horizontal pull shades''). ''Adolf Hitler: The Larry King Interview'' finds the Führer proclaiming himself a changed man in a 1999 CNN appearance (''I get up at seven, have half a melon, do the Jumble in the morning paper and then let the day take me where it will''). And ''Pen Pals'' imagines a correspondence between Princess Diana and Mother Teresa. (''Any new men?'' Di asks. ''You're so pretty but you always play it down.'')
As an MTV talk-show host, Stewart seemed sharper than his material, and his intelligence is evident in chapters about Vincent van Gogh (whose tortured attempts to chat with his brother on-line are documented in ''Vincent and Theo on AOL'') and Leonardo da Vinci (whose ''Lost Notebook'' contains sketches of an invention called the Ass Comb). He's also unafraid to lampoon religion: ''The New Judaism'' predicts that ''by the year 2010, Jewish life in America will have deteriorated to the point where a Seinfeld reunion special will be a non-sweeps event.'' Only a dated Gerald Ford parody falls flat.
Stewart's brutally witty book bodes well for his upcoming gig as anchor of Comedy Central's slash-and-burn mock newscast, The Daily Show. Naked Pictures reveals a basic truth that's too often forgotten by the shock-for-shock's-sake satirists of the South Park era: You've got to be smart to be a smart-ass. A-