The Chaos Class Is on Vacation (movie, 1977)

Lazy, uneducated male students mostly coming from money, share a very close band. They live together in the dormitory of this private highschool, where they daily plan their latest pranks on teachers or the other classes. Because of the financial crisis, the headmaster agrees to enroll female students. As the new students try to fit in, a struggle between both parties start, trying to prank the other part away. The prank war continues until PE-Teacher decides to take the class out on a trip for a becoming scouts.