The sub-genres usually conform to certain conventions, and each may appeal to a particular audience. Erotic spanking is the act of spanking another person for the sexual arousal or gratification of either or both parties. Interracial pornography typically employs ethnic and racial stereotypes in its depiction of performers and many of interracial pornographic films still include racial stereotypes, although the segregation of actors by race has diminished considerably. However, the tradition of bondage magazines continues in the form of art books of bondage photographs, published by mainstream publishers such as Taschen. It may also involve touching, rubbing, or pinching the nipples or other erogenous zones while masturbating. The interaction between tops and bottoms—where physical or mental control of the bottom is surrendered to the top—is anime hentai sometimes known as power exchange, whether in the context of an encounter or a relationship. The exact source and nature of the fluid continue to be a topic of debate among medical professionals, which is also related to doubts over the existence of the G-Spot. Rough sex pornography is similar to pornography featuring sadomasochism, and typically features a Top who humiliates and/or degrades a Bottom while being physically violent towards them. 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. Some restrict a policy of panties/nipple tape for females and some allow full nudity with explicit sexual interaction milf fuck allowed. Transsexual people Transman pornography features performers who were born female and who medically transitioned to male. Bisexual DVDs sell much better online than in adult video stores, possibly due to customers in stores feeling embarrassed to buy them. The principal characteristic of voyeurism is that the voyeur does not normally interact directly with the subject of his/her interest, who is often videos porno gay unaware of being observed.