The stigma of being gay or labeled naked milf as such has steadily eroded since the Stonewall riots began the modern American gay rights movement in 1969. Sex experts have praised various techniques gay movies that the performer can use during fellatio to increase their partner pleasure. Related genres include: Amateur pornography originally referred only to pornography produced by amateurs but now also includes professionally made pornography designed to appear as if it were amateur. Foot fetishism, foot partialism, foot worship, or podophilia is a pronounced sexual interest in feet. Simultaneous penetration of the mouth and either the vagina or anus. This may relate to fetishes such as voyeurism or cuckolding. Along with the penis, the scrotum is sensitive and considered to be an erogenous zone. Men and women may masturbate until they are close to orgasm, stop for a while to reduce excitement, and then resume masturbating. One-sided male nudity can also arise when a male disrobes as part of a male striptease. Women porn is often produced by women and aimed specifically at the female market - rejecting the view that men are turned on by porn but women only by a box of chocolates. The higher pay scale and profile within a production often leads to group scenes where a straight actor only tops. Group sex can occur between people of all sexual orientations and genders. 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. Bisexual DVDs sell much better online than in adult video stores, possibly due to customers in stores feeling embarrassed to buy them. Some productions are noted for sophisticated and/or experimental storytelling and animation techniques. It is commonly depicted in pornography, but very rarely in mainstream cinema. Partners can engage in penetrative sex, known as full swap, or choose to soft swap in which they engage only in non-penetrative sex.