That's basically the beginning of a series of misadventures, in which the two dumb-asses roll from one absurd situation into the next. A case of mistaken identity provides them with a villa to live in, and much of the film juxtaposes the happy-go-lucky idiots against the rich hipsters whose holiday they crashed, while trying to keep the fly a secret from everyone.
While never all that likeable, Manu and Jean-Gab at least make for an amusingly childish couple. That's no surprise: the two actors have a long-running chemistry and have been paired up in films before. The fly is done well, and Adèle Exarchopoulos (of Blue is the Warmest Color fame) steals her scenes as a slightly brain-damaged resident of the villa.
Those looking for character growth need to look elsewhere. Quentin Dupieux is just having fun here at the sunny French Riviera, as do most of the actors. With only 77 minutes of length, the film manages to just reach the finish before its welcome runs out. And a moral? Nah. Absurd dumb fun may still be dumb fun, but it's also still fun. Rotterdam audiences thought so too, and awarded the film a rating of 3.7 out of 5.