It is geared towards heterosexual men, who most typically define a threesome as such. The gaysex term BDSM dates back to 1969; however, the origin of the term BDSM is unclear and is believed to have been formed either from joining the term B&D with S&M , or as a compound initialism from B&D, D&S , and S&M. Cartoon pornography depicts illustrated or animated fictional characters in erotic and sexual situations. Bear features a combination of middle-aged, hairy or overweight males. Preggo pornography features pregnant performers and may include erotic lactation as a fetish. Biological anthropologist hentai porn Helen B. Group sex pornography features at least two men and two women , usually more, who all perform sex acts on each other. Positions can also be chosen specifically for added effects such as increased humiliation, elevation and suspension. A person may be porn milf sexually penetrated multiple times simultaneously. Internationally, hentai is a catch-all term to describe a genre of anime and manga pornography. The glans itself may widen and lengthen as the stimulation continues, becoming slightly darker in colour, while the gliding action of the foreskin reduces friction. In POV porn, the shooting style is generally similar to gonzo pornography, with the person receiving sexual gratification holding the camera him or herself—aiming it down at the actress or actor who is performing the sex act. By comparison, gonzo pornography puts the camera right into the action, often with one or more of the participants both filming and performing sexual acts, without the usual separation between camera and performers seen in conventional porn and cinema. The study also found that participants reacted positively to a much wider range of figures than a control group, even rating emaciated figures higher. A woman can use a secondary vibrator, between the dildo and her genitals, to get pleasure from pegging. Types of anal sex can also be a part of lesbian sexual practices. Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face.