In the heat of the moment, the cousin doesn't realize the sister is his real sister until it's too late. Instead of stopping, he's consumed by the taboo lust, driven by the sight of her ass shaking with each thrust. She screams in ecstasy, "Fuck me harder, make me your slut, yourGF!" as he pounds her, their bodies slapping together. They climax together, their fluids mixing, before collapsing, realizing the gravity of their incestuous act.