Stan the flasher (1990)

Claude Berri, who usually participates in films by directing them, here returns to the screen as Stan, an over-the-hill lothario, much given to quoting Shakespeare, who occasionally goes around naked under his raincoat and exposes himself to strangers, who are usually not interested in his primitive display of genitalia. It also appears that he is unable to sexually satisfy his much younger lover, and he suspects her of having another boyfriend. He earns his living tutoring students (mostly young girls) in English literature. When, in his frustration, he gropes one of the girls in her home during a tutoring session, she protests, her father (who is at home) beats him up, and he is sentenced to a jail term. There, he is teamed up with a slightly loopy murderer. When he gets out of jail, he finds his girlfriend has left for good, and ends his life.