Four teenage misfits - Will, Simon, Jay and Neil - have finished their A-levels and are about to leave Rudge Park Comprehensive, much to the relief of Mr. Gilbert, their sarcastic, cynical sixth form tutor. Within their final week of school, however, Jay's grandfather dies, Simon is dumped by his girlfriend Carli and Will discovers that his divorced father has unexpectedly married his much younger mistress. Depressed, the boys decide to go on holiday together and Neil books them on a trip to Malia, Crete.
Their accommodation in Malia is awful, but the boys meet four girls - Alison, Lucy, Lisa and Jane - in an empty bar during their first night out. Their initial meeting goes less than smoothly- Will chats to Alison and pokes fun at her cliched "Greek waiter boyfriend", Simon bores Lucy to death talking about Carli, Neil has a non-conversation with Lisa, and Jay "gets stuck" with the bubbly, if somewhat overweight Jane. The girls go on their way after Neil pulls two older women, but arrange to meet the boys the next day. Outside the bar, Simon sees Carli across the street. He talks awkwardly with her before being run over by a quadbike ridden by James, an obnoxious club rep and Carli's new squeeze. Carli reveals she is going to a boat party later in the week, and Simon pledges to meet her there.
The next morning, Will and Simon awaken to find Neil being given oral sex by a middle-aged woman and Jay sleeping face-down in an ants' nest outside. After sobering up, they go to meet the girls by their hotel pool. While there, Jay has his shorts pulled down by a local child and throws him into the pool in retaliation, only to find that the boy cannot swim. At the same time, Will gets into an argument with a family whose poolside sun-loungers were 'requisitioned' by the boys, tactlessly pointing out that their wheelchair-bound daughter 'doesn't even need a sun-lounger'. Having publicly humiliated themselves, the boys are quickly thrown out of the hotel.
Outside, Jay argues with Simon over his continuing obsession with Carli and they fight in the street. Will and Neil separate the pair and drag them off in different directions. Desperate to buy a ticket for the boat party, Simon attempts to sell his clothes to James, but never gets paid for them. Meanwhile, Jay angrily tears up two tickets he secretly bought for them as a surprise. He and Neil then go to a nightclub hoping to meet more girls, only to witness a male stripper performing autofellatio on stage. The duo subsequently run into James and his friends, who ridicule and threaten them until they leave.
Later that evening, the four boys meet back at the bar and bury the hatchet. Before long, the girls turn up and suggest that they all go skinny dipping at the local beach. Jane attempts to kiss Jay, but he is embarrassed by her size so she leaves him behind. Will has better luck with Alison until he stumbles across her Greek boyfriend having sex with another woman; Alison then runs off in tears. Lucy and Simon appear to be growing closer until he sees Carli on the beach and leaves Lucy alone in the sea.
Eventually, the boys are able to obtain tickets for the boat party. On board, Carli kisses Simon passionately in order to make James jealous, and Simon realises he is being used. Jay apologises to Jane, and she takes him into the toilets to perform oral sex on him. After finishing, they encounter James, who mocks Jane's weight and tries to extort money from Jay in order to snort cocaine. Jay complies, but gives him a 20 note that had been concealed in his anus as a bribe for 'corrupt foreign cops', resulting in James unknowingly walking around with faeces on his nose for the rest of the day. After a conversation about 'ethics', Neil and Lisa decide to be together and celebrate by dry-humping each other.
Meanwhile, Alison hunts out Will and asks to be his girlfriend. He eagerly accepts as Simon finally realises that Lucy, who gave him her ticket so that he could attend the party, is more worthy of his attention than Carli. Simon then attempts to jump off the boat and swim to her on the beach as a grand romantic gesture, but nearly drowns in the process and has to be airlifted to shore. As several paramedics load him into an ambulance, Lucy rushes over to him in concern and the two reconcile.
After the boat party is over, the other boys and girls visit Simon in hospital, and once he recovers they all spend the rest of their holiday together as couples. Eventually, the four boys head home to the UK, looking forward to the next stage of their lives. As they meet their families at the airport, their girlfriends exit the same terminal and introduce themselves to the boys' parents as the film ends. In a final scene during the credits, Mr. Gilbert is seen riding a quad-bike through the streets of Malia in his underwear.