Sensations (1975)

Two pretty women, Margaret and her best friend, arrive in Amsterdam to meet her boyfriend who's a photographer. They get exposed to very liberal sexual situations very soon and while conventional naive and timid Margaret isn't all that into it, her friend wants in on the action that includes lesbian and all other kinds of sex. They even witness a golden shower. Temptations of this odd sexual wonderland become harder and harder for Margaret to resist and her adventure ends in a most lustful and bizarre fashion.