Exhibitionist pornography features performers, usually female exposing themselves in public and spans simple flashing to public sex. Some couples use a threesome milf fuck as a way to develop a love triangle . Masturbation involves touching, pressing, rubbing or massaging a person genital area, either with the fingers or against an object such as a pillow; inserting fingers or an object into the anus ; and stimulating the penis or vulva with an electric vibrator, which may also be inserted into the vagina or anus. Facesitting when a woman or a young girl sits on a man face. The anal and rectal tissues are delicate and do not provide natural lubrication, so they can easily tear and permit disease transmission, especially if lubricant is not used. Contact mutual masturbation One person touching another person to masturbate. This is sometimes the case for punishment scenes between master/slave couples or for some extreme or edgeplay scenes which may include abductions, rape play, or interrogation. In some areas, there are laws stating it is not legally possible to consent to be killed, and elsewhere it may still be legally dubious . Masturbation has been depicted in art since prehistoric times and is mentioned and discussed in very early writings. Buck Angel is the best-known actor in this genre. Studies indicate that anilingus is a rare sexual practice between anime hentai women. Sexual arousal from a particular body part is classified as partialism. It can be combined with fellatio and the woman may move her breasts up and down on the penis for an additional stimulation, usually before the man reaches orgasm. Non-contact group More than two people masturbating in the presence of each other in a group but not touching each other. The surfacing of gaysex sex tapes has become so common that some are leaked as a marketing tool to advance or establish a media career. Fistees who are more experienced may take two fists . Freud, however, considered such extensions of sexual interest to fall within the range of the normal, unless marked out by exclusivity .