Guess which one is the son's penis! Yu Kawakami VOSS-034

Let Kawakami Yu and her son challenge a lewd little game! Guess which one is the son's penis!? If you guess right, you get a prize; if you guess wrong, you'll be punished by having a stranger's penis inserted into you in front of your son! The penises are lined up for the wife to masturbate; if they were really mother and son, they wouldn't guess wrong, right?