Reviewer's grade: C-
Simon Pegg is slumming it. How else to explain that the guy who starred in and co-wrote the hilarious "Shaun of the Dead" and "Hot Fuzz" is now relegated to the formulaic idiocy of "Run Fat Boy Run?"
Pegg portrays Dennis, a lingerie-store security guard still carrying a torch for the beautiful Libby (Thandie Newton), whom he left pregnant and standing at the altar five years earlier. Now, Libby has a new suitor, a too-good-to-be-true American named Whit (Hank Azaria), whom we know is a jerk because he's a hedge fund manager, pop culture's whipping boy du jour. Whit, an experienced runner, is about to compete in a charity marathon.
What better way for Dennis to win back Libby than to enter the marathon and show up his new rival? From this modest premise, director David Schwimmer (from TV's "Friends") crams this crass comedy with enough lame slapstick and gross-out gags to make Rob Schneider look like Woody Allen. PG-13