Le grand sabordage (1973)

Two youngsters, a boy and girl barely into their teens, set up housekeeping together after dropping out of school. They have very little money and end up living in a rooming house. They spend their time playing, coming up with slogans, and writing them on available walls. Their relationship is mostly fraternal, so the boy doesn't understand the girl's jealousy when he begins receiving attention from an older woman. When the girl undertakes drastic measures, he begins to understand. This Canadian film is in French, with a French director.