plompzakken means: Plompzakken refers to a Dutch sex act in which the woman wears a belt around their waist that she keeps tight. The man can then open her vagina wide enough that he is able put his cock inside. Accidents occurred during plompzakken. The belt broke and left the man with his dick inside the woman. It is not easy, but it can be very tight. (in Community Dictionary, added by Darryl Richardson)