Gay-for-pay describes male or female actors, pornographic stars, or sex workers who self-identify as heterosexual but who are paid to act or perform as homosexual professionally. Preggo pornography features pregnant performers and may include erotic lactation as a fetish. Dwarfs or midget pornography features gay cock performers who are dwarfs/midgets. Barebacking usually refers to a conscious and deliberate choice to forgo condoms. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. Individuals are also sometimes abbreviated when referred momsex to in writing, so a dominant person may be referred to as a Dom for a man, and a Domme for a woman. Transgender pornography features performers who cross-dress for sexual gratification, either for themselves or for their partners. Hardcore pornography is pornography that depicts penetration or extreme fetish acts, or both. Both sexes sometimes apply lubricating substances to intensify sensation. Clothed male, naked female is one-sided female nudity in which one or more females are nude while one or more men are clothed. Men may find stimulation of the anus, rectum, and adjacent organs enjoyable. Internal ejaculation shots are a comparatively recent development in pornography; they are not found in early pornographic films. Yaoi is anime or manga that features gay males . Films with risqué content commenced to be produced soon after the invention of the motion picture in the 1880s. Normal quantities anime hentai of ejaculate range from 1.5 to 5.0 milliliters . Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. Female ejaculation is the expulsion of fluid by the paraurethral ducts through and around the human female urethra during or before an orgasm. Sigmund Freud considered foot binding as a form of fetishism. A few extremely flexible males can reach and stimulate their penis with their tongue or lips, and so perform autofellatio.