Detective magazines, comic books and early fetish magazines In the early 20th century, Detective magazines covertly provided a way of publishing bondage imagery. For instance, Amateur Allure has a trademark shot where the sexually performing cameraman circles a handycam around the sexually performing model head. Pro-am pornography is sub-genre of amateur pornography that refers to professionally made porn that features amateur actors/actresses, often appearing for the first time in a pornographic film. Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. Cuckolding can also be mixed with other non-monogamous relationship arrangements with which it has substantial overlap such as Swinging, wife-swapping, gay hentai open relationships, and polyamory, etc. Femdom features BDSM scenes in which the dominant partner is female. The other person may do the same during or after. Cum shots typically do not appear in girl-girl scenes and orgasm is normally implied by utterances, cinematic conventions, or body movement. The full-weight body-pressure, moisture, sex odors and darkness can be perceived as powerful sexual attractions or compulsions. Voyeur pornography may also include shots of topless women on topless beaches who are unaware of the cameras but may legally be photographed due to the public setting. A scene where many women have sex with one man is referred to as a reverse gang-bang. Additionally, the buttocks give an indication of the shape and size of the pelvis, which impacts reproductive capability. Sub-genres can also be classified into the characteristics of the performers or the type of sexual activity on which it concentrates, and not necessarily on the lesbian milfs market to which each sub-genre appeals. This makes varying degrees of stimulation hot gay sex an integral part of oral sex for many men. Tentacle erotica can be consensual, but frequently contains elements of non-consensual sex. Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer.