Christopher Guest's latest effortlessly hilarious mockumentary is even funnier than its very similar predecessor Waiting For Guffman. This time a national dog show, rather than a small-town talent show, is the focusing event for the improv riffs of Guest's expert cast. The movie is mostly a series of improvised scenes between well-matched comic duos, the funniest of which are neurotic urbanites Parker Posey and Michael Hitchcock, wealthy sugar mama Jennifer Coolidge and her lover/kennel boss Jane Lynch, schlub Eugene Levy and his oversexed wife Catherine O'Hara, and perhaps best of all, dog show commentators Fred Willard and Jim Piddock. Willard pours it on as the folksy gabber who knows nothing about dog show protocols and Piddock is a superbly patient straight man. Much of Best in Show's premise is anticipated not only by Waiting for Guffman but by Errol Morris's classic "real" documentary about pet cemeteries and their patrons, Gates of Heaven, but the easygoing overabundance of comic talent and belly laughs overshadow such quibbles. The movie's just plain funtastic.