La miel (1979)

Don Agustín, a ridiculous school teacher, visits the mother of his young student Paco. Paco's mother, a sexy woman, asks don Agustín to exert influence over her son to make him being successful. The old teacher accepts the challenge pressured by his older sister, eager to spend all her money playing bingo. But don Agustín soon begins to suspect that Inés, the mother of Paco, holds the oldest profession in the world.