Die Feuerzangenbowle (1970)

The title refers to the Feuerzangenbowle punch consumed by a group of gentlemen in the opening scene. While they exchange nostalgic stories about their schooldays, the successful young writer Dr. Johannes Pfeiffer realizes he missed out on something because he was taught at home and never attended school. He decides to make up for it by masquerading as a student at a small-town high school. At the school, he quickly gains a reputation as a prankster. Together with his classmates, he torments his professors Crey, Bömmel, and Headmaster Knauer with adolescent mischief. His girlfriend Marion unsuccessfully tries to persuade him to give up his foolish charade. Eventually, he falls in love with the headmaster's daughter and discloses his identity after provoking the teachers into expelling him from school.