Participants usually derive pleasure from this, even though many of the practices—such as inflicting pain or humiliation or being restrained—would be unpleasant under other circumstances. The nipples are erogenous zones, and vigorous stimulation of them during masturbation usually causes the penis to become erect more quickly than it would otherwise. Most soft crush fetishists avoid being placed under the same label as hard crush fetishists, believing that crush films with larger animals give the entire group a bad label. First found in softcore gay boy porn movies and erotic thrillers, depictions of lesbianism entered mainstream cinema in the 1980s. In the context of consensual erotic activities, sadism and masochism are not strictly accurate terms; there is a significant difference from the medical or psychological usage of both terms. Transsexual porn star Wendy Williams has stated that transsexual porn is classified as Straight Specialty. 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. Greater economic and social freedom allowed them gradually to be able to determine how they could form relationships and families. A facial is a form of non-penetrative sex, though it is generally performed after some other means of sexual stimulation, such as vaginal sex, anal sex, oral sex or masturbation. A pearl hentai sex 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 techniques which may work for one individual can be difficult or uncomfortable for another. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and momporn H-computer games. Incest pornography can feature actual relatives, but the main type of this pornography simply uses actors of similar looks to suggest family relationship. The related term twinkle-toes, which implies that a man is effeminate, tends to be used in a derogatory manner.