Fans of Shaun of the Dead and Hot Fuzz won't want to keep pace with Simon Pegg on this particular outing. Run Fat Boy Run is a dispiriting would-be comedy whose characters fall into two categories: idiots, and good people acting like idiots. In his feature directing debut, David Schwimmer seems eager to inflict as many actors as possible with the same kind of spasmodic schtick he endured in his last seasons as Ross Geller, especially British character actor Dylan Moran, whose appearance as Pegg's best friend is otherwise without purpose. But the most ill-conceived character is Pegg's Dennis himself. We're meant to believe he found his impending nuptials to Thandie Newton's Libby so suffocating, he had to ditch her on their wedding day, even though she had a bun in the oven. Not only are his reasons never explored (other than being male, which makes him a genetically predisposed flight risk, according to screenwriters Pegg and Michael Ian Black), but Libby is in so many ways the perfect woman -- attractive, fun, hip, and cool -- that his decision smacks of ludicrousness, even if she weren't pregnant. Then again, ludicrousness informs most of this movie, especially the protracted finale, which must have struck somebody as inspirational. There was hope that a sharp comic mind like Hank Azaria could do something original with Dennis' rival, and in fact, at first he seems more than the typical outré fiancée whose flaws are apparent to everyone but the heroine. Unfortunately, he becomes that guy in short order. Even if the tone weren't wrong, even if the structure weren't goofy, and even if the characters weren't poorly written, there would still be the glaring dubiousness of referring to Pegg as "fat." Yet another question about Run Fat Boy Run that never got asked.