The most 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. The volume of semen that is ejaculated depends on several factors, including the male health, age, degree of sexual excitement, and the time since his last ejaculation. Works in this genre may be considered adult for any number of reasons. New York photographer Irving Klaw also published illustrated adventure/bondage serials by fetish artists Eric Stanton, Gene Bilbrew, Adolfo Ruiz and others. The term bondage describes the practice of Physical restraining. Specific sex acts Anal Anal pornography naked milf features anime hentai anal penetration with a penis, dildo, other objects, or some combination of them. Since mammary intercourse is a non-penetrative sex act, the risk of passing a sexually transmitted infection that requires direct contact between the mucous membranes and pre-ejaculate or semen is greatly reduced. Bukkake is a sex act portrayed in pornographic films, in which several men ejaculate on a woman, or another man. Rainbow parties were covered on The Oprah Winfrey Show in 2003, and became the subject of a juvenile novel called Rainbow Party. Content featuring male bisexuality has been a growing trend since the advent of internet pornography. 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. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. Men may also rub or massage gaysex the glans, the rim of the glans, and the frenular delta. Hamedori is a genre of Japanese pornography in which a male adult video actor or director serves as the camera operator. Urolagnia is a form of salirophilia in which sexual excitement is associated with the sight or thought of urine or urination. As a form of non-penetrative sex, it can be done for its own enjoyment or as foreplay.