Pegging films include Strap It On , Babes Balling Boys , Strap Attack, Strap-on Sirenz, Strap-on Chicks, Boss Bitches , various movies produced by LEDA Studios, and San Francisco-based Men In Pain. However, gay pornography in the modern world is mostly concentrated in the making of home videos , cable broadcast and emerging video on demand and wireless markets, as well as images and movies for viewing momsex on the Internet. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. Lolita pornography caters to ephebophiles. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. While some fantasize about a giantess who is slightly taller than himself, others are interested in giantesses that are hundreds or even thousands of feet tall. 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. Most bisexual porn hentai sex is made by small production companies rather than the major studios. Although there may be no connection between coprophilia and sadomasochism , the limited data on the former comes from studies of the latter. Mammary intercourse has sometimes been considered a perversion. A scene where many women have sex with one man is referred to as a reverse gang-bang. 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. Behind the Green Door was one of the first pornographic films to feature sex between a white actress with a black actor gaysex . A bisexual threesome may involve a man having sex with a man and a woman, the woman having sex with a man and a woman, or all three having sex with each other. Such video tapes are often released without the consent of their subjects, and could potentially damage celebrities careers.