A busty mom undergoes a physical fitness challenge by shaking her breasts! She changes into sportswear in front of her son without a bra, engages in deep abdominal kisses, jumps rope with exposed breasts, tests grip strength by masturbating, and even performs a breast-assisted ejaculation test to measure breast strength! The second half is a continuous endurance mother-son incest competition, counting the number of times she ejaculates! She engages in incest in positions conducive to pregnancy and on dangerous days, continuing the sweaty incestuous act even after pregnancy!