Plot

Two straight, single Brooklyn firefighters pretend to be a gay couple in order to receive domestic partner benefits.

Chuck Levine and Larry Valentine are friends and Brooklyn firefighting partners. Widower Larry, who still mourns the death of his wife Paula, is having problems changing the beneficiary on his insurance policy from Paula's name to his children's. He is worried about his children's future if he were to be killed in the line of duty, and is contemplating quitting his job for something less risky, but he also does not want to forfeit his firefighter's pension as he also see it as a safety net for his children. Larry saves Chuck's life on one of their calls. So when Chuck tells Larry that he owes him one, Larry takes him up on his offer. Larry's favor: despite both being heterosexual, that they enter into a domestic partnership, in name and paper only, to provide that much needed protection for Larry's children. Chronic womanizer Chuck reluctantly but eventually agrees. The one person who knows for a certainty that they are both straight is their boss, Captain Phineas J. Tucker. Their plan hits a snag when Larry believes that they are being investigated by the pension department for possible fraud, which means that Chuck has to move in with him and his kids. They consult the advice of a lawyer, Alex McDonough, who adds an extra layer of complexity to the situation as Chuck in particular is attracted to her and believes she could be the one and only for him. Her legal advice coupled with her wanting Chuck to be her new best girlfriend makes it even harder on him.—Huggo

Veteran New York City firefighters Chuck Levine (Adam Sandler), a womanizing bachelor, and Larry Valentine (Kevin James), a widowed father, are the pride of their Brooklyn firehouse, Engine 506/Ladder 223. Their fellow firefighters include Renaldo (Nicholas Turturro), David (Jonathan Loughran), Duncan (Ving Rhames) (a recent transfer to their team and not very talkative), Karl (Gary Valentine) and others.

During a sweep of a burned building, a segment of floor collapses on Chuck, but after Larry rescues him from the debris. Chuck vows to repay him however possible. Experiencing an epiphany from the incident, Larry tries to increase his life insurance policy but discovers that a lapse in the paperwork after his wife Paula's death 1 year earlier prevents him from naming his children, Eric (Cole Morgen) and Tori (Shelby Adamowsky), as primary beneficiaries. The beneficiary now can only be changed in the event of birth, death and marriage. Changing them to his kids would require paperwork to be filed and will take time. Larry believes that as a fireman his job carries tremendous risks and hence is not willing wait for the paperwork to be corrected. The insurance company representative Sara Powers (Rachel Dratch) suggests that Larry find a new spouse that he can name as his beneficiary. Teresa (Mary Pat Gleason) is Larry's housekeeper. Tori is into soccer and sports, but Eric is effeminate and likes musicals and can do a perfect split.

Inspired by a newspaper article about domestic partnerships, Larry asks Chuck to enter a civil union with him. Although at first Chuck declines, he is reminded of his debt to Larry and finally agrees. Larry says that Chuck is the only one he can trust to take care of his kids and his money when he is gone. Chuck and Larry become domestic partners and Chuck becomes Larry's primary beneficiary in the event of his death. Soon, New York City investigator Glen Aldrich (Matt Winston) arrives to inquire about their partnership, suspecting fraud. Based on his observations Glen recommends that an investigator be assigned to Chuck and Larry's case, who would drop in unannounced over the next 3-4 months.

Chuck and Larry decide to enlist the help of a lawyer, Alex McDonough (Jessica Biel), who suggests that they get married. Alex says that the state has been acting tough on gay domestic partnerships since the Bensley case, where one Government employee extended their health benefits to his friend, under the guise of a "domestic partnership". Both were prosecuted for fraud and did time in jail. The pair travel to Niagara Falls, Ontario, Canada for a quick same-sex marriage at a wedding chapel (where they hire a crazy homeless person (Blake Clark) to be their witness), and Chuck moves in with Larry and his children.

At a gay benefit costume party (which Alex invites them to), the party-goers are confronted by homophobic protesters outside the venue, whose leader, a minister (Rob Corddry), calls Chuck a "faggot". Chuck punches him, causing the event to be published in a newspaper. With their apparent homosexuality and marriage revealed at work, the pair come under fire. Chuck and Larry are heckled, while their fellow FDNY firefighters refuse to work or even play basketball alongside the couple. Their only ally is Fred G. Duncan, an angry, intimidating firefighter who comes out to a very surprised Chuck. Alex gets more comfortable with the guys and invites Chuck for girl's day out, where she go shopping and tries on new dresses in front of Chuck in the dressing room, giving him a hard on. Larry's effeminate son Eric is harassed in school by a homophobic bully - but he surprises everybody by easily winning the fight. During the ordeal, the previously homophobic pair come to understand what it is like to be persecuted and become more accepting of homosexuality.

Chuck becomes romantically interested in Alex after the two spend time together but finds himself unable to get close to her because she thinks he is gay. Meanwhile, city agent Clinton Fitzer (Steve Buscemi) arrives to investigate the couple. The strain on both Larry and Chuck leads to a verbal fight and also working different shifts. Larry asserts that Chuck's constant absence to spend time with Alex is jeopardizing their ability to maintain the ruse of their relationship, and Chuck responds by instructing Larry to move on from Paula's death.

There was also a petition to have Chuck and Larry thrown out of the firehouse. This prompts Larry to confront the crew about their personal embarrassments on the job that Chuck and Larry helped them overcome. After this a call goes out and before they go on the call Larry even goes as far as to say: "Oh! A fire. I hope its not a big one because the faggot who's been saving your sorry asses thanks to you is on another shift". After Larry's shift is over, Chuck and Larry reconcile their differences.

The marriage soon comes under fire, as numerous women provide testimonies as to having slept with Chuck in the recent past, and the couple is called into court to defend their marriage on charges of fraud. They are defended by Alex, and their fellow firefighters arrive in support, after they realize all Chuck and Larry done for them over the years, and how they were treating Chuck and Larry. Fitzer interrogates both men, who testify that they genuinely love each other (albeit in a platonic fashion). As his final demand, Fitzer asks for the pair to kiss to prove that their relationship is physical, but before they do so, they are interrupted by Captain Phineas J. Tucker (Dan Aykroyd), who finally reveals that their marriage is a sham and that they are both straight.

Tucker attempts to save Chuck and Larry by claiming that he would have to be arrested as well, since he knew about the fake marriage, but failed to report it. This prompts the other firefighters to each claim a role in the wedding in a show of solidarity. Unfortunately, with these revelations, Chuck, Larry, and other firefighters are sent to jail, but they are quickly released after negotiating a deal to provide photos for an AIDS research benefit calendar. The deal including pleading guilty to fraud, which would reduce the charges to a misdemeanor. Two months later, Duncan and Alex's brother, Kevin (Nick Swardson) are married in Canada at the same chapel as Chuck and Larry were.

At the wedding party, Larry finally moves on after the death of his wife and talks to a new woman, while Alex tentatively agrees to a dance with Chuck. The film ends when Lance Bass sings, and little Eric tap-dances.