Pornography can be classified according to the physical characteristics of the participants, fetish, sexual orientation, etc., as well as the types of sexual activity featured. BDSM has become an umbrella milf xxx term for certain kinds of erotic behavior between consenting adults. 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. High heel pornography involves women or men dressed in high heeled shoes. It may involve sexual attraction to women who are pregnant or appear pregnant, attraction to lactation, or attraction to particular stages of pregnancy such as impregnation or childbirth. Bareback sex is physical sexual activity, especially sexual penetration, without the use of a condom. The fundamental principles for the exercise of BDSM require that it naked celebrities should be performed with the informed consent of all involved parties. Such films continued to be produced but could only be distributed by underground channels. See Gay-for-pay. Matsuo used amateur actresses in his videos, and he usually traveled to their hometowns for hentai sex the filming. Fisting involves the insertion of one partner entire hand into a vagina or the anal cavity. Scenes of multiple penetration are common in pornography. As amateurs in a single segment of a multi-part video, the actresses are typically paid only about 50,000 yen . Another variant of reality pornography consists of normal couples that are filmed by professionals, in which case the only obvious distinction from amateur pornography is the higher quality of production, filming and editing. The speed of the hand motion will vary from person to person, although it is not uncommon for the speed to increase as ejaculation nears and for it to decrease during the ejaculation itself. Cum swapping pornography involves performers trading semen between their mouths. In some areas, there are laws stating it is not legally possible to consent to be killed, young gay porn and hentai porno elsewhere it may still be legally dubious .