Well, those kooky, bad-taste Farrelly brothers are back, those semen-hair-gel guys, those rotund-Gwyneth-Paltrow guys; and this time they've brought us a comedy about conjoined twins, played by Matt Damon and Greg Kinnear. Only this time they've gone so far in the other direction - the good-taste need to be squeaky clean about it all - that they've taken some of the fun out of their story.

Damon and Kinnear are Bob and Walt Tenor, the joint proprietors of the Qwikee Burger in Oak Bluff, Martha's Vineyard, where they guarantee your meal delivered in three minutes or you don't pay for it. But Walt has bigger ideas; he's currently playing the Robert Morse role in the local production of "Tru," with of course Bob tagging along behind him. But as much as Walt loves the spotlight Bob has stage fright in public and is subject to panic attacks. The boys carry paper bags for him to breathe into. Nevertheless, Walt persuades him to come west so he can make his mark in Hollywood; it works because Bob has been emailing a girl for three years who happens to live there. He's also been cropping Walt out of the photos he sends her, afraid that she'd drop him if she found out that they're, well, stuck on each other. "We're not Siamese," he shouts at a heckler; "We're American!"

Walt gets an agent, Morty O'Reilly (Seymour Cassel), who's so far behind the times he's still trying to hide Rock Hudson's sexual orientation from the public, and is hired by Cher (as herself) to costar in a television detective series, "Honey and the Beas," simply so she can break her contract with the network; who, after all, would want to watch conjoined twins on television? But the show turns out to be the hit of the season, and Cher is stuck with it. Meanwhile, the truth can no longer be hidden from Bob's email friend May Fong (Wen Yann Shih), but not to worry: she's subject to panic attacks as well. Their neighbor at the Rising Star residence motel is pretty April (Eva Mendes), who will end up with Walt.

The boys are joined at the liver, and Bob has more of it than Walt, so an operation to separate them could be dangerous for Walt, which is also supposed to explain why Walt looks older than Bob; he's aging faster. So the underlying question is whether or not they should have the operation. As I say, the film takes itself a bit too seriously.