In this happily dopey movie, Christopher Meloni is Dave Stewie, gym teacher and failed Olympian. Mr. Stewie dreams of redeeming himself by leading his students to first place in a national fitness challenge. The obstacle to winning is a clumsy pupil whose mom, anxious since her husband died in a potato-sack race, insists he wear a helmet. Meloni, whose brow is ordinarily as stern as Bert the Muppet's, is having a relaxed, silly time here. Amy Sedaris is even better as the school principal, secretly in love with Mr. Stewie and his well-fitted shorts.