The Farrelly brothers are the producers and mentors of a movie which displays their trademark mix of explosively non-PC bad taste and warm sentimentality. It stars Johnny Knoxville as a guy who pretends to be mentally disabled so that he can win a gold medal at the Special Olympics. It's a funny idea, and Knoxville actually doesn't do too badly. But despite the bad-taste laughs, and there are a few, there is something queasy about the inevitable segue into fuzzy feelgood acceptance.