I've Got You, You've Got Me by the Chin Hairs(1979)

Original title: Je te tiens, tu me tiens par la barbichette

In this satire, a police detectiveis investigating the disappearance and kidnapping of the host of a television dance show. However, instead of finding his man, he is trapped into becoming a contestant on a children's quiz show. What's worse is that he becomes a very successful contestant.