Sameer (Salman Khan) is a hot-tempered person with terrible anger management issues ever since his parents passed away in his childhood. After he beats up a group of goons who tried to assault his girlfriend Roma (Amrita Arora), she breaks up with him due to his bad temper. Thus, as per his horoscope, he is very unlucky in love. With a broken and heavy heart and to get away from everything, he leaves for Goa to take up a job as a lifeguard, where he meets Rani (Priyanka Chopra) and instantly falls in love with her. After many attempts at befriending her and a rough start with her father (Amrish Puri), Rani and Sameer become friends.
However, Sameer's ill fated luck comes into play as he still has some rough incidents with her father and Rani, too gets angry with him since she overhears him saying bad things about her to Pandit ji (Rajpal Yadav).
Further trouble arrives in the form of Sunny (Akshay Kumar), who moves into the same house as Sameer and shares a room with him. He too meets Rani, falls in love with her and decides to cause further trouble by getting closer to her through the mistakes Sameer makes. This causes a lot of trouble between the two. It is evident that Sunny is out to ruin Sameer's relationship with Rani so that he can steal Rani away from him. This can further be shown when he takes credit for Sameer as the latter had helped her with money for a fashion show and had made the mistake of remaining anonymous and calling himself her "well-wisher". Also, he goes to the extent of taking credit for a painting of Rani that Sameer has made. He kidnaps Rani's dog, Tommy and blames Sameer for it.
These actions aggravate Sameer and ignite his temper, making his relationships rocky. Matters are not helped when Sameer gets into the bad books of Suraj Prakash (Satish Shah), a man whom he had met on the train to Goa, who had scared Sameer into staying awake for the whole night and whom Sameer had later put on guard duty for night times for 3 months at the club where he was working and who, Sameer later realises, is Rani's uncle.
Also, a misunderstanding occurs when Sameer's grandmother who is partially blind arrives and mistakes, Rani's mother for Rani while trying to persuade her into marrying Sameer. Sameer, who goes to sort out the situation gets caught in an embarrassing position with Rani's mother. Rani, who is shocked and disgusted is advised by her mother that Sameer had not been at fault in that situation. She also says that Rani should carefully deliberate on whom she loves more- Sameer or Sunny.
Disgusted and completely out of hope and patience, Sameer decides to leave Goa forever. As he is leaving, Sunny arrives and taunts him on how he got close to Rani through the latter's mistakes. Sameer says that he has had enough of dreaming of Rani and wishes Sunny all happiness as he leaves.
Sunny however tries to have the last laugh as he taunts Sameer again. This time, Sameer loses his temper completely. He rounds on Sunny and chases him through the streets right through to a crowd at a cricket stadium, where India and Pakistan are supposed to be playing a friendly match. Deciding to have one last try, he enters the field after breaking through security, takes the mike from Kapil Dev, the guest of honour, and uses it to apologise to Rani and her parents very sincerely for his past mistakes. Saying so, he confesses his love for her and asks her to marry him in front of the whole crowd, coupled with motivation from spectators and players alike. Rani runs out to the field and embraces him, thus reuniting with him.
At the end, Sunny arrives and reveals that he is actually Arun, Sameer's childhood friend who had come to Goa, (after getting information from Sameer's grandmother when he had gone to the latter's house the first thing after returning from America after nineteen years), for a cure to Sameer's anger management issues, all the time pretending to be his enemy. He had revealed the same to Rani and her parents earlier. Sameer, then realises who he is and is reunited with his old friend as well. The film ends with Arun conducting Sameer and Rani's marriage.