...And Give Us Our Daily Sex (1979)

Verónica and her friend (Laura Gemser) are two very sexy bisexual nurses who live upstairs from a rather boring couple and their teenage son. In a science class at school he learns how to build a periscope, and uses it to spy on the nurses sexual antics. Meanwhile, Albert's mother is being even naughtier than her precious boy, sneaking off for some extra-marital sex while her hair-obsessed husband is at the salon, having his follicles tended to. This all gets to be too much for the young lad as he soon starts to suffer from unexplained pains in the groin area. It all comes to a head when the parents of the boy ask the nurses to come and check him out and Laura proceeds to realize what the problem is. So she promptly wanks the boy off in front of his parents.