play game where mother and son secretly underwater

This movie features a cheating mother who engages in an incestuous relationship with her son in secret, while her husband is unaware. The son fucks his mother in a challenging game where they have to ejaculate inside within sixty minutes without getting caught by the father, with a prize of 100,000 yuan at stake. The central kink of this scene revolves around the taboo and secretive nature of their incestuous acts, including oral sex and ejaculation, all while trying to avoid detection.