Recently, a friend made the observation that one of the most important parts of growing up is realizing that Robin Williams was never funny. Hence Williams making movies for younger and younger audiences, such as RV, which gets its biggest laugh from raining feces. RV is a family road-trip farce in the proud tradition of National Lampoon’s Vacation and, uh, National Lampoon’s European Vacation. But RV’s bickering Munro family are no Griswolds, and when a nice Southern family they reject as rednecks inexplicably keeps trying to make friends, Cassie Munro (teen pop songstress Joanna “JoJo” Levesque) echoes your thoughts when she screams, “What do they like about us? We’re not even that appealing!” Director Barry Sonnenfeld, who has executed better middlebrow fun in the past with The Addams Family and Men in Black, settles here instead on the kind of broad slapstick derived from an escalating series of worst-case scenarios. At least he keeps Williams on a short leash—with the exception of a painfully protracted Ebonics riff—letting a talented supporting cast, which includes Jeff Daniels and Cheryl Hines, handle most of the jokes that are actually funny.