In transforming 'King Lear' into a potty-mouthed jape, Moore is up to more than thumbing his nose at a masterpiece. The bells on my coxcomb drooped in despair.' After a lively sexual encounter with Lear's daughter Goneril, the Fool reflects, 'What a bitter bitch to cast me out while my bum still burned with the blows of her passion. That's relatively mild stuff compared with the eponymous narrator's playfully frank way of putting things.

'Oh, we are but soft and squishy bags of mortality rolling in a bin of sharp circumstance,' goes one of Gloucester's soliloquies here, 'leaking life until we collapse, flaccid, into our own despair.' He freely distorts the action of 'Lear,' adds and alters characters and throws his narrative voice around in a sustained act of Shakespearean ventriloquism. Wodehouse to Eddie Izzard as inspirations, participates eagerly in the tradition of irreverent homage. Moore, who acknowledges everyone from Oscar Wilde to P.G. 'MacHomer,' with Homer Simpson in the title role, has made several visits to the Bay Area. Tom Stoppard saw 'Hamlet' through the lens of two minor characters, in 'Rosencrantz and Guildenstern Are Dead,' and also produced a 15-minute version of Shakespeare's play. Playing fast and loose with Shakespeare is a long-standing practice, as Moore notes in a postscript, aptly titled 'You Cheeky Git.' Nahum Tate's 1687 version of 'King Lear,' which appended a happy ending to the play, held the stage for several centuries. The result is a Bardic stew liberally seasoned with slapstick, sex, groaner puns, anachronisms and plenty of cheerfully curdled Elizabethan wordplay. Some of the other appropriations are slyer. Lifts from 'Macbeth,' 'Hamlet,' 'A Midsummer Night's Dream,' ' Julius Caesar,' 'Romeo and Juliet' and 'Love's Labour's Lost' are overt. Not content to restrict himself to that capacious and penetrating tragedy itself, Moore rummages around in a dozen or so of Shakespeare's other plays for characters, plot points, imagery and dialogue. In 'Lamb' (2003), he set out to narrate Jesus' coming-of-age story in a 'Gospel According to Biff, Christ's Childhood Pal.' In his rambunctious new book, 'Fool,' Moore undertakes nothing less than a prose retelling of 'King Lear.' Give San Francisco comic novelist Christopher Moore full marks for plunging into deep waters. By Christopher Moore ( William Morrow 311 pages $25.95)

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