Courier (movie, 1986)

Ivan Mirosnikov, a cheeky young man in the Gorbachev era, is trying to figure out what to do with his life (he's not in college, and the 2-year mandatory military service is looming large ahead of him). Meanwhile, he lives with his divorced mother, and works as a courier at a Russian newspaper. Through his job, he meets patronizing Professor Kuznetzov and his rebellious daughter Katya. To annoy the professor, Ivan claims to have an affair with Katya. To his surprise, Katya backs his story up.