This chapter opens with a discussion on penis size. Individuals have their preferences but the data swerve sharply toward penis size being irrelevant except for a small proportion of women who like the aesthetics of a larger penis and those gay men who are hooked on size as an erotic trigger. The chapter next talks about the vagina and highlights that the vulva is outside, and the vagina is inside. It then talks about circumcision. As of now, no major medical organizations are suggesting that all newborn infants be circumcised for health reasons. Instead, the view is that the procedure should be available to any family that wants it and should be reimbursed by insurance. The chapter further talks about the G-spot in women, testosterone, and biological sex.