Emetophilia pornography involving vomiting and gagging. A few extremely flexible males can reach and stimulate their penis with their tongue or lips, and so perform autofellatio. BDSM actions can often take place during a specific period of time agreed to by both parties, referred to as play, a scene or a session. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a prelude to, or as part of, masturbation. Shemale is a term primarily used in sex work to describe a trans woman with male genitalia combined with female secondary sex characteristics, usually including augmented female breasts, from breast augmentation and/or use of hormones. A homosexual threesome would involve either three men or three women. Foot fetish pornography features heavy emphasis on the feet of the participants, either in combination with kissing and genital sex or in the context of acts such as trampling or crush fetishism. This can, however, redirect semen into the bladder . The prostate gland is one of the organs that contributes fluid to semen. There is no singular or archetypical behavior; therefore, a wide gay porn range of thought patterns and behaviors exist, but all tends to be a harmless and efficacious release from some kind of pressure. A pearl necklace is a slang term referring to a sexual act in which a man ejaculates semen on or near the neck, chest, or breast of another person. Some do not use the diapers at all, for arousal, or bladder and bowel movements. The porn industry and viewing public were shocked by the then-taboo spectacle of a white woman having sex with a black man. Some restrict a policy of panties/nipple tape for females and some allow full nudity with explicit sexual interaction allowed. The inside of a smotherbox is often padded to provide support for their neck and prevent their head from moving. Transsexual porn star Wendy Williams has stated that transsexual porn is classified as Straight Specialty.