Andrews cross or spreader bars. This is commonly called double vaginal penetration or double stuffing. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Mammary intercourse has sometimes been considered a perversion. Mammary intercourse is known as titty-fucking, titfuck, or a titjob in the United States, as well as tit wank or French fuck in the United Kingdom - the latter term dating back to the 1930s; while a more jocular equivalent is a trip down mammary lane. The loose and direct camera work often includes tight shots of the genitalia, unlike some traditional porn. Crush pornography features objects being crushed by an actress or actor, who generally plays an overtly dominant role. In Japan, point of view pornography is referred to as hamedori . No causal relationship is known between masturbation and any form of mental or physical disorder. Lying face down one may use the hands, one may straddle a pillow, the corner or edge of the bed, a partner leg or some scrunched-up clothing and hump the vulva and clitoris against it. While some fantasize about a giantess who is slightly taller than himself, others are interested in giantesses that are hundreds or even thousands of feet tall. Today, religions vary in their views of masturbation; some gay boy porn view it as a spiritually detrimental practice, some see it as not spiritually detrimental, and others take a situational view. Its gain in prominence has been attributed to its depiction in the film Pecker, which was released in 1998. Erotic spankings are commonly combined with other hentai videos forms nude milfs of sexual foreplay. Sadomasochism refers to the aspects of BDSM surrounding the exchange of physical or emotional pain. Some anthropologists and sociobiologists believe that breast fetishism derives from the breasts similarity to buttocks, but instead provide sexual attraction from the front of the body. The primary subjects of pornographic depictions are pornographic models, who pose for still photographs, and pornographic actors or porn stars, who perform in pornographic films.