This makes varying degrees of stimulation an integral part of oral sex for many men. Group sex pornography features at least two men and two women , usually more, who all perform sex acts on each other. Typically featured are hitting, choking, name-calling and hair-pulling. Men may also rub or massage the glans, the rim of the glans, and the frenular delta. Common phrases used to refer to these individuals are chicks with dicks or the derogatory term shemale, although these are gay video generally considered pejorative among transwomen. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. Cum shots typically do not appear in girl-girl scenes and orgasm is normally implied by utterances, cinematic conventions, or body movement. The queening stool is also related to a smotherbox, which also allows the person under the seat to be locked in place, restrained by the neck as in a set of stocks. This genre also features male-on-male fellatio through a small hole made in a bathroom divider. On May 27, 2010 the television program The Doctors discussed the topic with dozens of teens, parents, and professionals. In POV porn, the shooting style is generally similar to gonzo pornography, with the person receiving sexual gratification holding the camera him or herself—aiming it down at the actress or actor who is performing the sex act. Voyeur pornography may also include shots of topless women on topless beaches who are unaware of the cameras but may legally be photographed due to the public setting. Most bisexual porn is made by small production companies rather than the major studios. To avoid soreness from this resulting friction, some may prefer to use a personal lubricant, masturbation cream or saliva during masturbation. Lolita pornography features women who are 18 years old or slightly older, who pretend to be underage teen girls. Many cultures describe pain as an aphrodisiac. Being forced to wear diapers as a form of humiliation is sometimes a behavior encountered in sexual masochism.