The Inbetweeners Movie, it induces numerous guffaw moments... Also see The Inbetweeners TV series if you haven't already, 3 seasons in total each having 6 episodes.
The series is about 4 lads who are in sixth form and the movie is based on their summer vacation after they finish their A-levels. Even though the film has a lot of British humour and slang everyone could probably relate to it. Another recommended British Teen drama is Skins which had Dev Patel from Slumdog Mililionaire in it. It is more extreme (i.e. sex, drugs and crime) then The Inbetweeners but still a good laugh nonetheless.