Once the reigning kings of lowbrow, gross-out setpieces, the Farrelly brothers sparked a scatological revolution with Dumb And Dumber, Kingpin, and especially There's Something About Mary, making it hard to watch a multiplex comedy with both eyes open. Their queasy mix of the sick and the sentimental reached full-blown multiple-personality disorder in their last film, Shallow Hal, a well-meaning and occasionally touching gagfest that offset sophomoric fat jokes with weepy visits to the pediatric burn ward at a local hospital. While "mature" isn't the right word to describe Stuck On You, an agreeably silly farce about conjoined twins, the Farrellys are showing signs of settling down, and the change suits them. Pratfalls and juvenile gags remain their stock in trade, along with a special affinity for misshapen outcasts and ordinary joes, but they've abandoned shock humor in favor of a gentler, more humane, and far more approachable form of idiocy. Still married to high concept, they update the Dumb And Dumber formula by attaching a marginally wiser pair at the hip, reworking the symbiotic-twin dynamic from Dead Ringers into something closer to the three-legged race at the company picnic. No explanation is given for why Matt Damon and Greg Kinnear, the film's enthusiastic stooges, look nothing like each other, but they have definite qualitative differences: While Damon slips into the paunchy embodiment of a blue-collar slob, Kinnear still can't shake the residual smugness of his late-night-TV roots. Content to flip burgers forever in their greasy-spoon restaurant near Martha's Vineyard, Damon indulges his brother's unlikely dream of parlaying his triumphant one-man show about Truman Capote (Tru) into a shot at Hollywood stardom. For obvious reasons, Kinnear suffers a few predictable setbacks when they first arrive in Hollywood, but he catches a break when a chance run-in with Cher leads to a starring role in a network TV show. Looking to wriggle out of a contract for an awful program called Honey And The Beeze (she plays Honey, opposite a character named Beasley), Cher exercises her right to choose a leading man by casting Kinnear, but the studio calls her bluff. With this playful knockoff of The Producers, the Farrellys poke fun at celebrity without indulging in too much inside baseball; even though a few stars and directors make cameo appearances, the Farrellys' affection lies with the fringe-dwellers. Though it's still too reliant on a sloppy, gag-a-second style, Stuck On You gets through the arid stretches by leaning on some winning performances, most notably from a hilarious Seymour Cassel as a retired agent who apparently hasn't negotiated a deal since Hollywood's Golden Age. It may take some time for the Farrellys to produce smarter, more character-driven comedy, but they've finally taken a baby step in the right direction.