Testosterone discourages fat storage in these areas. Irrespective of the legal or social view of pornography, it has been used in a number of contexts. In the gay pornography industry, which uses amateurs as well as professional actors, the term gay-for-pay refers to actors labeled or believed to be straight but who engage in same-sex sexual activities for money. Buttocks are sometimes emphasized in pornography, where they are often referred to as booty. Men may also rub or massage the glans, the rim of the glans, and the frenular delta. Participants who exert sexual control over their partners are known as dominants or tops while participants who take the passive, receiving, or obedient role are known as submissives or bottoms. Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses . Sexual orientation Pornography features an increasing variety of combinations of actors by their sexual orientation such as lesbian, gay, bisexual, and transsexuals in addition to traditional heterosexual roles. Femdom features BDSM scenes in which the dominant partner is female. It is geared towards heterosexual men, who most typically define a threesome as such. Dwarfs or midget pornography features performers who are dwarfs/midgets. Masturbation is the self-sexual stimulation of the genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. 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. Yaoi is anime or manga that features gay males . In Canada, Teletoon offers up its own Teletoon at Night programming black gay porn block. Spanking can be administered in a number of spanking positions. 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. Women oriented pornography is sometimes referred to as sex positive pornography.