The Ringer (2005)

Steve Barker (Johnny Knoxville) finds himself in a predicament. His friend Stavi, whom he was forced to fire, loses several fingers in an accident, and he has no way of covering the cost of surgery without health insurance. Meanwhile, his gambling uncle, Gary (Brian Cox), is racking up a huge debt. Needing money quickly to help Stavi and Gary, Barker reluctantly goes along with his uncle's plan to fix the Special Olympics, with Barker posing as an athlete -- but the competition is steep.