Paul Aufiero is a parking garage attendant who lives with his mother in Staten Island, New York. He relentlessly follows the New York Giants football team. He and his friend Sal faithfully attend each Giants game; however, as they can't afford tickets, they content themselves with watching the games on a battery-powered TV in the stadium parking lot. Paul is also a regular caller to the Sports Dogg's radio talk show, where he refers to himself as "Paul from Staten Island," rants in support of the Giants, and berates his mysterious on-air rival, Philadelphia Eagles fanatic "Philadelphia Phil". Paul's family criticizes him for doing nothing with his life. He disregards their scorn and happily devotes himself to his beloved team. One day Paul and Sal spot Giants star and Paul's favorite player Quantrell Bishop and his entourage in Staten Island. They follow Bishop to a drug deal in Stapleton. Though the pair see Bishop buying something, they naively fail to recognize the transaction. Paul and Sal then follow Bishop into a strip club in Manhattan where they eventually introduce themselves. All goes well until the two fans innocently mention that they saw Bishop in Stapleton. Bishop becomes enraged and brutally beats Paul, who wakes up in a hospital. Following the incident, Bishop is suspended from the team. Paul's personal-injury lawyer brother Jeff and NYPD Detective Velardi pressure Paul to bring charges against Bishop, but Paul refuses, worried about the effect on the Giants' performance if they lose their star linebacker. The charges against Bishop are eventually dropped and he returns to the team. Jeff then files a $77 million civil lawsuit against Bishop as Paul's legal guardian, claiming Paul is mentally incompetent and can't bring the lawsuit himself. When a reporter phones Paul to ask him "about the lawsuit," Paul becomes livid and confronts Jeff as he sits on the toilet. Both Jeff and Paul's mother start to pressure Paul to get mental help. Philadelphia Phil researches Paul on the Internet and reveals on Sports Dogg's show that the victim of the Quantrell Bishop beating is in fact "Paul from Staten Island", humiliating him. Paul heads for Philadelphia to confront Phil. Disguised as an Eagles fanatic, Paul identifies Phil in a local bar and gains his trust as they watch the Giants and Eagles play the season's pivotal final game. As the Eagles dominate the Giants, the crowd in the bar begins to deride the Giants in increasingly enthusiastic fashion, much to Paul's consternation. When time runs out and the Eagles fanatics celebrate their victory, Paul follows Phil into the men's room and pulls a gun on him, shooting Phil multiple times. Phil, lying shocked on the men's room floor, stares at his hands, which are now covered in red and blue, the Giants' colors. The gun is then revealed to be a paintball gun. Paul utters "Eagles suck!" and flees from the bar. Paul is arrested and imprisoned for the assault. Sal visits Paul in jail and reveals to him the Giants' schedule for the following season. A key game coincides with the week Paul is scheduled to be released—Paul is overjoyed and says "It's going to be a great year".
Big Fan received mostly positive reviews from critics. Rotten Tomatoes gives the film a rating of 86%, based on 88 reviews, and an average rating of 7.1/10. The website's critical consensus reads, "Featuring Patton Oswalt's sympathetic portrayal, Big Fan humorously and effectively captures the dark and lonely world of a sports fanatic." Metacritic gives the film a score of 70 out of 100, based on 27 critics, indicating "generally favorable reviews." The New York Times gave the film a positive review, describing it as an "agreeably low-key and modest film."
