Opis: Kishan Singhania (Anil Kapoor), a wealthy print-media owner is married to the suspicious-minded Kajal (Lara Dutta), who thinks he is having an affair with another woman, though he is faithful to her and never wills to betray her anyway.
His friend Prem Khanna (Salman Khan), a rich businessman has the opposite situation has many affairs with other girls, even though he is married to Pooja (Esha Deol), who is very trusting.Kishan's employee, Shekhar "Sunny" Gupta (Fardeen Khan) (who is the star photographer of Kishan's newspaper and always gets the most scandalous stories), accidentally falls in love with Sanjana Saxena (Celina Jaitly). Shekhar was writing an article on suicides and tears off the page and throws it away. It lands on Sanjana, who thinks Shekhar is trying to commit suicide. She pursues Shekhar to prevent him from taking his own life (he was at suicide point to take some pics for his article). Sanjana tracks down Shekhar and tells his house owners about Shekhar's plans to commit suicide. Shekhar is thrown out of the house.
Shekhar considers Kishan his elder brother and they both would do anything for each other. Kishan allows Shekhar to stay in his outhouse, till he is able to sort his life out. Shekhar goes to market to buy rat poison for the outhouse. Sanjana sees this and thinks this is Shekhar's new way of committing suicide. She brings the entire neighborhood to break into the outhouse to stop Shekhar from committing suicide.
Sanjana is in love with Shekhar as she feels that no boy has such dedication for their girlfriend in this day and age.Kishan publishes sleazy photos of minister Param Kumar Gupta/PK (Boman Irani), which Shekhar had taken, while PK was frolicking with random girls. Dhamini Gupta (Pratima Kazmi) is PK's wife and keeps on a tight leash.As Kishan takes Prem's photos with his girlfriend and threatens to inform Pooja, Prem sends Bobby Kaushik (Bipasha Basu), a call girl to seduce Kishan (he makes a bet for rs 2 L, if Bobby has sex with Kishan). The plan is that he'll fall into Prem's trap.
Kajal starts spying on Kishan and sees him giving money to a woman and her kid. She accuses Kishan of having a 2nd family. But Kishan slaps Kajal and explains that this is the family of his employee who lost both his legs in an accident a few months ago. He would not accept money from Kishan, so Kishan would buy his paintings via his wife, to support the family. Kajal is ashamed at her behavior and decides to trust Kishan more. Prem uses this to convince Kishan to have an affair with Bobby.Kishan plans to meet Bobby at his home while Kajal travels to Ajmer. As her ticket is left at home, she returns and finds Bobby with Kishan in their outhouse, which they'd given Shekhar to live in. Kishan tells her that Bobby is Shekhar's wife. Sanjana hates lies and doesn't tolerate other women in a man's life.
Kajal enters Bobby and Shekhar in the best couples contest and Shekhar is afraid that somehow Sanjana will find out. PK is the chief guest at the event and knows Bobby from the escort services that he usually hires his girls from. He sees Bobby as Shekhar's wife.The following weekend Kishan goes with Shekhar to Judge Mrityunjay Saxena (Anjan Srivastav), who is Sanjana's father, to ask for Sanjana's hand in marriage for Shekhar. Kishan says that his wife saw 9/11 from up close and is mentally traumatized. Hence she doesn't accompany him anywhere. Meanwhile Bobby is arrested with her client at a hotel. She claims she is married, and takes the inspector to meet Kishan at the Judge's house, as she knew Kishan and Shekhan would be there. Kishan steps forward and says that Bobby is his wife, and that her client is her brother.A few days later Sanjana meets Kajal while shopping and the 2 go for coffee. Sanjana invites Kajal to her wedding.
At the wedding, PK is again invited and is confused to see that Bobby is Kishan's wife and that Shekhar is getting married to Sanjana. Thats when Kajal arrives at the wedding. Kajal finds Shekhar at the wedding in a groom's dress. Shekhar says that its his friends wedding, who has bought an exact duplicate dress for him. Kishan manages to get Kajal out of the wedding by faking chest pains.
The doctor sends Kishan and Kajal away for vacation to Mauritius. Unfortunately, Shekhar is at the same hotel for his honeymoon. Turns out Bobby is also staying at the same hotel with her client. Somehow Shekhar and Kishan manage the situation. PK arrives in Mauritius.Things go wrong when Kajal sees Bobby with her client & Shekhar with Sanjana. She believes Shekhar & Bobby are both cheating on each other. Kajal confronts Sanjana, and accuses her of roaming around with a strange man (Shekhar). SAnjana accuses Kajal of seducing a strange man (Kishan, who has abandoned his wife Bobby).
Kishan and Shekhar make a plan to go to each other's wife and praise the other. But back home, Sanjana had gone to Kajal's house and vice-versa to apologize. So, when Kishan thinks he is meeting Sanjana, he actually meets Kajal (who was hidden behind a bookshelf) and says he is flirt, while Shekhar is pure. Shekhar does the same (wrt Kishan) with Sanjana.
When this plan fails, the guys make a plan to scare their wives with divorce. But the wives send them divorce notices instead.To Save Shekhar and Kishan, Prem tells Kajal and Sanjana that Bobby is his 1st wife. After he married Bobby in secret (as their parents were totally opposed to the match), his father found Pooja at a Barista and married Prem to Pooja (as his 2nd wife). While Prem is narrating his story, Pooja arrive and is heartbroken. Prem tells her that he was only protecting his friends, who were having an affair with Bobby. Shekhar says that Prem was the one who got Kishan tangled with Kishan. Pooja is hurt as her trust has been betrayed and leaves.Prem learns that Bobby's husband is in coma and she has to give the hospital rs 20000 per day, to keep him alive. This is why she does what she does. Prem promises to pay for treatment.
Shekhar and Kishan apologize to their wives, but Prem decides to commit suicide. Kishan and Shekhar go to save him but Shekhar ends up dangling off a cliff with Prem. While trying to save them, Kishan also ends up dangling off a cliff.
The ladies forgive the men, arrange a rope and save their husbands. Pooja tells Prem that she knew all along that he was lying to her. Prem is ashamed and decides to be loyal to her from then on.It is hinted at the film end, however, that the three friends haven't fully turned over a new leaf with the entrance of Nisha/Beach Girl (Sameera Reddy) in a cameo.