In some scenes or relationships it may be impossible for consent to be withdrawn in the middle of a scene, or the bottom may have the ability to revoke consent for a relationship as a whole, but not for a particular scene. 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. 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. Transsexual lesbian hentai porn star Wendy Williams has stated that transsexual porn is classified as Straight momporn Specialty. Snuff pornography involves the actual death of any of the participants, consenting or otherwise, simulated death is not considered snuff. Each participant may engage in any type of sex acts with one or both of the others, such as vaginal, anal or oral sex or mutual masturbation. The term soft crush refers to the more common fetish surrounding videos involving inanimate objects or small invertebrates being crushed, while the term hard crush refers to such videos involving larger animals with vertabrae, and arguably more pain-susceptible animals . Lesbianism has been a theme in erotic art since at least the time of ancient Rome, and many regard depictions of lesbianism to be erotic. Lucky Pierre is slang for a person performing both receptive and insertive anal and/or vaginal sex simultaneously during a threesome, being positioned between the two partners. Reflective of its views on sexuality and culture, Japanese pornography delves into a wide spectrum gay movies of heterosexual, homosexual, and transgender sexual acts in addition to unique fetishes and philias. 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. If ejaculation is onto the other person face it can be called a facial.