Goon

Doug Glatt (Seann William Scott) is a very nice but unintelligent man who feels ostracized from his family, his father and brother both being doctors. One day he visits a minor league hockey game with his friend Ryan (Jay Baruchel). Ryan taunts the visiting team during a fight and one of their players climbs into the stands. Doug, in defence of his friend, headbutts the hockey player and knocks him out, which prompts the rest of the crowd to cheer him. Soon after, Doug gets a phone call from the coach of his home team who offers him a job as an enforcer, a player whose role is to protect his teammates and acts as a deterrent by hitting or fighting opposing players who take liberties with his teammates.

Wikipedia: Goon
Official movie site: Goon
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