An Australian cult movie about surf teenagers with, I guess, the Puberty blues...

Meet Sue, a teenage Australian girl in the late 70s, whose life mainly consists of doing what everyone else does - watch the surfing boys and have sex with the same surfing boys. The girls have to follow lots of strange customs, e.g. do not eat or go to the bathroom when a boy is around.
 The afternoons are spent on the beaches, in the backseats of car or at home-alone-parties where sex and alcohol are the main ingredients. Parents and teachers are trying to straighten the kids out, but that is not easy.