Snuff pornography involves the actual death of any of the participants, consenting or otherwise, simulated death is not considered snuff. Other possibilities are possible, such as a man having sex with two women who are having sex with each other. Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent on self-identification and shared experience. As with most forms of sexual activity, anal sex participants risk contracting sexually transmitted infections . Can also include auto-fellatio, or performing oral sex on oneself. Freud, however, considered such extensions of sexual interest to fall within the range of the normal, unless marked out by exclusivity . One or more of the participants may engage in autoerotic sexual activity, such as masturbation, possibly without physical contact with the other participants. Along with the penis, the scrotum is sensitive and considered to be an erogenous zone. Masturbation has been depicted in art since prehistoric times and is mentioned gay twinks and discussed in very nude milfs early writings. 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. Mutual masturbation is a sexual act where two or more people stimulate themselves or one another sexually, usually with the hands. The 1979 U. Japanese rope bondage is distinguished by its use of specific katas and aesthetic rules. Fetish cuckolding can have a wide range of expression, from pillow-talk fantasy between monogamous partners to extreme alternative lifestyles, depending on the couple. Hentai is the various forms of Japanese pornography, including H-manga, H-anime, and H-computer games. Individuals who can change between top/dominant and bottom/submissive roles—whether gay hentai from relationship to relationship or within a given relationship—are known as switches, though the term switch in this context is occasionally seen as derogatory and is rejected by many who might simplistically fit the definition.