Most bisexual porn is made by small production companies rather than the major studios. Pregnancy fetishism is a context where pregnancy is seen by individuals or cultures as an erotic phenomenon. Common positions include lying on back horny milfs or face down, sitting, squatting, kneeling or standing. The term sadomasochism is derived from the words sadism and masochism . When the interest in a particular subject is obsessive, the behavior may be described as stalking. It is sometimes combined with BDSM features. A pornographic work is characterized as hardcore if it has any hardcore content, no matter how small. The smotherbox is placed on a stable surface. 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. Other objects such as ball point pens and thermometers are sometimes used, although this practice can lead to injury and/or infection. Patricia Hill Collins, an African-American writer, theorizes gay movies that this is derived from a stereotype that those of black descent are promiscuous, and their buttocks are objectified by porn as a result. Jerk off instruction features a performer encouraging or instructing the viewer to masturbate, often culminating in a countdown at the end of which the viewer is invited to induce orgasm. Dwarfs or midget pornography features performers who are dwarfs/midgets. Pornography is often distinguished from erotica, which consists of the portrayal of sexuality with high-art aspirations, focusing also on feelings and emotions, while pornography involves the depiction of acts in a sensational manner, with the entire focus on the physical act, so as to arouse quick intense reactions. Once hentai porn insertion is complete, the fingers are either clenched into a fist or kept straight. Real medical shots or videos may violate privacy laws in some countries. Pornography may be presented in a variety of media, including books, magazines, postcards, photographs, sculpture, drawing, painting, animation, sound recording, film, video, and video games.