Plot:
Steve Barker (Johnny Knoxville) hates his job but after over two years of working, receives a promotion. His first duty is to fire his friend Stavi, who is the janitor. Steve fires Stavi, but hires him to work around his apartment. Stavi gets three fingers cut off in a lawn-mower accident, and reveals that he does not have health insurance. Steve must raise $28,000 within two weeks to pay for the surgery to re-attach his friend's fingers. His uncle Gary (Brian Cox), owes $40,000 in gambling debts and suggests that they fix the Special Olympics in San Marcos, Texas in order to solve both of their financial problems. Steve, who competed in track and field in high school as well as being in the drama club, enters the Special Olympics in the guise of a high functioning young man with learning difficulties named Jeffy Dahmor. Gary, assuming that Steve will easily defeat the legitimate contenders, bets $100,000 that reigning champion Jimmy Washington will not win the gold medal. Despite initially being disgusted at pretending to be mentally challenged, Steve goes along with it for Stavi.
During the competition, Steve falls in love with Lynn (Katherine Heigl), a volunteer for the Special Olympics. During this time, six of the other contestants see through Steve's ruse. Since they hate the egotistical, arrogant champion Jimmy and want to see him lose, they decide to help Steve defeat Jimmy. Steve begins to feel guilty for his actions, and tries to confess his sins to a priest but is instead beaten up.
At the final competition, Steve does not actually win; his friend Glen does, with Steve coming in third behind Jimmy. During the medal ceremony Steve admits that he is not developmentally disabled, reveals his actual name, and that he does not deserve his medal. He then gives his medal to Thomas, who had come in fourth. Uncle Gary still ends up winning his bet, since the condition was that Jimmy would not win. Lynn, upset at Steve for lying, slaps him.
Six months later, Steve has quit his job and is working in theater, helping produce a play with the friends he made during the Special Olympics, as well as Stavi, who got his fingers reattached. Glen and the others trick Lynn into coming to the theater, so Steve starts to apologize. Lynn, who was originally shocked at the ruse, already forgives him because Stavi told her why Steve pretended to be developmentally disabled. Lynn is relieved, and they kiss.
During the end credits, the play of Romeo and Juliet is performed which ends with the Kids of Widney High performing Arethra Franklin's "Respect".