Oral Sex Introduction: Cunnilingus is oral sex performed on a woman. It is done by using the mouth to stimulate the female genitals. This includes the external genitals (the vulva), as well as the opening to the vagina, and especially, the clitoris. Fellatio is oral sex performed on a man. It is done by using the mouth and tongue to stimulate the penis and scrotum, including in particular the back of the head of the penis, the underside of the shaft of the penis and the skin on the testicles. Analingus is oral sex performed on the anus. This channel deals not only with information about how these different types of behaviors are performed, but also about pleasure and avoiding sexually transmitted infections (STIs).