The third helping of ''American Pie'' offers little more than crumbs. Half the franchise's core cast (including Mena Suvari, Chris Klein, and Tara Reid) chose to skip the big fat geek wedding of recent college grads Jim (Jason Biggs) and Michelle (Alyson Hannigan). You can hardly blame the no-shows, considering that the inept direction of ''How High'''s Jesse Dylan reduces American Wedding to a groin-numbing onslaught of sexual-humiliation and emission-ingestion gags.
Among the rote drolleries: Jim's dad (Eugene Levy) catches his son with his pants down, literally, twice in the first 15 minutes; perennial horndog Steve Stifler (Seann William Scott) downs a doggy-doo truffle; and Jim accidentally garnishes the wedding cake with his pubic shavings. Even gifted Christopher Guest cronies Levy, Jennifer Coolidge, and Fred Willard can't make ''American Wedding'''s comic wind any mightier.