Some men also enjoy anal stimulation, with fingers or otherwise, without any prostate stimulation. Many cultures describe pain as an aphrodisiac. What seems clear from the historical record is that much of the lesbian material in pornographic texts was intended for a male readership. Typically featured are gay sex hitting, choking, name-calling and hair-pulling. 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. Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or more men are clothed. Crush pornography features objects being crushed by an actress or actor, who generally plays an overtly dominant role. The name was coined from the title of the controversial book. 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. The first explicit pegging scene is believed to have been in the 1975 pornographic film The Opening of Misty Beethoven. Masturbation is the self-sexual stimulation of the genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. Biological anthropologist Helen B. Most bisexual porn is made by small production companies rather than the major studios. In S/M, the Sadist is usually the Top and the Masochist the Bottom, but these roles are frequently more complicated or jumbled . They may be noted for using risqué themes, graphic violence, sexuality or black comedy in a manner that is unsuitable for younger audiences. Snowballing or snowdropping is the human sexual practice in which one person takes someone else semen into his or her mouth and then passes it to the mouth of the other, usually through kissing. Specific sex acts Anal Anal pornography features anal penetration with a penis, dildo, other objects, or some combination of them.