No causal relationship is known between masturbation and any form of mental or physical disorder. Following World War II, during a period of social repression when governments actively persecuted homosexuals, women developed networks to socialize with and educate each other. The name was coined from the title of the controversial book. Women who perform in lesbian pornography often do not consider themselves lesbian or bisexual. In humans, females generally have more round and voluptuous buttocks, caused by estrogen that encourages the body to store fat in the buttocks, hips, and thighs. In S/M, the Sadist is usually the Top and the Masochist the Bottom, but these roles are frequently more complicated or jumbled . Masturbation is the self-sexual stimulation of the genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. The industry generally refers to such hentai videos films as adult films, which is part of adult entertainment. Works in this genre may explore philosophical, political or social issues. It is typically animated pornography, as the legal age to be featured in a pornographic film in Japan is 18. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. Such gay cock documents have not been recognized as being legally binding, nor are they intended to be. The actual height of the giantess within the fantasy may vary depending on the individual. The cover can have hinges or be a separate part. The most big tit milf common male masturbation technique is simply to hold the penis with a loose fist and then to move the hand up and down the shaft. Both sexes sometimes apply lubricating substances to intensify sensation. In Japan, point of view pornography is referred to as hamedori . This is commonly called double vaginal penetration or double stuffing. 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.