Sometimes one or more fingers may be inserted into the vagina to stroke its frontal wall where the G-spot may be located. Clothes wetting: The person is sexually aroused by wetting one clothing or observing another person doing so. Interactive pornography, available in CD-ROM and DVD format, allows the viewer to select the particular acts performed at any one time, sometimes with the camera providing a first person view. Transgender pornography features performers who cross-dress for sexual gratification, either for themselves or for their partners. Animal masturbation has been observed in many species, both in the wild and in captivity. The strategies and tactics that are used to smuggle one of the couple into and out of the toilet undetected are as important or almost as important as the urination. The prostate momsex gland is one of the organs that contributes fluid to semen. The term sadomasochism is derived from the words sadism and masochism . Lolita pornography features women who are 18 years old or slightly older, who pretend to be underage teen girls. Group sex most commonly takes place in a private sex party or semi-public swinger gathering, but may also take place at massage parlors or brothels or, in some jurisdictions, at purpose-built locations such as sex clubs. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a prelude to, or as part of, masturbation. Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. Common positions include lying on back or face down, sitting, squatting, videos gays kneeling or standing. There is, however, no third party camera work involved. The other person may do the same during or after. This makes varying degrees of stimulation an integral part of oral sex for many men. It is also known colloquially anime hentai as gushing or squirting, although these are considered to be different phenomena in some research publications.