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 . Although milf fuck pornography has usually focused on heterosexuality, due to the prevalence of the heterosexual orientation, explicit gay material has a long history as well, which reaches back to Greek antiquity, if not to prehistory. These scenes may either have the cameraman directly engaging in sex or merely filming others having sex. Tentacle rape or shokushu goukan is found in some horror or hentai titles, with tentacled creatures having sexual intercourse with female characters. The genres of pornography are based on the type of activity featured and the category of participants, for example mateur pornography is a category of pornography that features models, actors or non-professionals performing without pay, or actors for whom this material is their only paid modeling work. People may engage in anilingus for its own sake, before anal fingering or penetration, or as part of foreplay. Celebrity sex tapes are amateur or professionally-made recordings of sex anime hentai acts, as performed by a celebrity and their partner. Since the 1980s, many practitioners and organizations have adopted the motto safe, sane and consensual, commonly abbreviated as SSC, which means that everything is based on safe activities, that all participants be of sufficiently sound/sane mind to consent, and that all participants do consent. Other young gay porn possibilities are possible, such as a man having sex with two women who are having sex with each other. The object or situation of interest is called the fetish; the person who has a fetish for that object/situation is a fetishist. Fisher said that perhaps, the fleshy, rounded buttocks attracted males during rear-entry intercourse. Bondage/BDSM Bondage pornography features performers tied up or constrained in various ways.