At long last, Matthew McConaughey has chosen the perfect vehicle in which to highlight his slacker radiance: He plays the aptly named Tripp, a 35-year-old yacht salesman who still lives with his mommy (Kathy Bates) and daddy (Terry Bradshaw). Tripp uses the folks to break up with girls he feels are getting too attached: He brings them home for a night of foolin’ around, then waits for Dad to barge in before springing the news he still lives at home. Works every time, at least until he brings home Paula (Sarah Jessica Parker), who doesn’t blanch at the news. But that’s only because Tripp’s folks have hired her to lure their boy out of the nest; she’s a paid girlfriend . . . fine, a whore. Failure to Launch has all the gravitas of a midseason-replacement sitcom. But beneath the sitcom sheen, there’s a darker movie about broken people who use convenient, pitiful excuses to keep from growing up. You laugh at them, but you also have sympathy.