An uptight dad-to-be (Robert Downey Jr.) hitches a cross-country ride with a garrulous wannabe actor (Zach Galifianakis) in this shaggy road comedy. Todd Phillips' (The Hangover) film is essentially a re-boot of Planes, Trains and Automobiles, in which two deeply incompatible people are forced to travel together, encountering many comic mishaps until -- awww -- they kinda start to like one another. (This version is R-rated though, so there's plenty of f-bombs and a masturbation scene that will make you -- and your dog -- uncomfortable.) Downey is a fine comic actor, and he delivers his rebukes here with plenty of withering disdain. The chewy, gooey heart of the film lies within Galifianakis' rotund form; he's the sad, lonely clown, whom we root for, but who is still dumb enough for us to laugh at. Jamie Foxx, Danny McBride and Juliette Lewis turn in expected cameos, and several cars are spectacularly wrecked. You'll laugh, in spite of your higher brain functions, but I'm not sure I ultimately bought the film's feel-good bromance conclusion.