The Mischief Makers
Les Mistons (original)
Durante un caluroso verano, cinco niños se dedican a espiar a Bernadette y Gérard, una pareja de amantes. Aprovechando que Gérard se va con una expedición alpinista, los niños mandan a Bernadette una provocativa postal. (FILMAFFINITY)
Starring Gérard Blain, Bernadette Lafont, Michel François, Alain Baldy, Robert Bulle, Henri Demaegdt, Dimitri Moretti, Daniel Ricaulx
It's a comedy movie, and has a rating of 7.1 out of 10 from Imdb which is usually fine for this kind of movie.
Watch it here
Not found streaming from Brazil.