Rated 2.0 An office worker (Ben Stiller) sees his best friend (Jack Black) strike it rich by inventing a spray that eradicates dog poop. The title is Envy, and for 10 or 15 minutes, it looks like that’s going to be the theme, too. But Steve Adams’ script quickly goes roaring off on a hysterical tangent that has Stiller accidentally killing Black’s white horse and enlisting a disheveled wino (Christopher Walken) to help him try to cover it up. (Yes, it’s true: The film literally ends up beating a dead horse.) Stiller and Black have a few good moments scattered about more or less at random, and Walken once again has fun slumming in a role unworthy of him, but they and director Barry Levinson are unable to make sense of Adams’ insane mess. As the stars’ wives, Rachel Weisz and Amy Poehler are wasted.