If you believe, as I do, that America is joined at the hip to the rest of the world but often in denial about it, then this cheerful comedy from the politically incorrect Farrelly brothers (There’s Something About Mary) about similarly conjoined twins who refuse to acknowledge all the ramifications of their condition is bound to have some allegorical resonance. Leaving behind their burger joint in Martha’s Vineyard, the pair go west to LA, where one (Greg Kinnear) wants to pursue an acting career and the other (Matt Damon) has a chance to meet his romantic pen pal (Wen Yann Shih). The actor lands a sitcom role opposite Cher (playing herself) and his brother frantically tries to conceal his condition from his sweetheart. Much of this is hilarious as long as one can stay sufficiently removed from the realities of conjoined twins. With Eva Mendes, Seymour Cassel, and, also playing themselves, Griffin Dunne and an uncredited Meryl Streep. PG-13, 119 min. (JR)