Kasimir, der Erfinder (1986)

Kasimir Glück's sex life is restricted to once-a-month by his migraine-stricken wife (Uschi Karnat). After a particularly lacklustre sex act he spends some time in his workshop to design a device (looking like a light switch mounted on a piece of plastic) that guarantees instant arousal. Indeed it works perfectly on his wife, and the couple realize that there is a commercial opportunity. Several copies are manufactured and the Glücks go on their separate ways to sell it door-to-door. Obviously, the aroused customers are in instant need of a sexual partner, and our enterpreneurs are happy to oblige. At the end of the day Kasimir's sales tactics have failed miserably, but his wife made a bundle.