They may regard it as an enhancing element of their sex lives or as their primary form of sexual activity. In S/M, the Sadist is usually the Top and the Masochist the Bottom, but these roles are frequently more complicated or jumbled . 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. Sometimes one or more fingers may be inserted into the vagina to stroke its frontal wall where big tit milf the G-spot may be located. Tentacle erotica can be consensual, but frequently contains elements of non-consensual sex. A sex party is a gathering at which sexual activity takes place. The term BDSM dates back to 1969; however, the origin of the term BDSM is unclear and is believed to have been formed either from joining the term B&D with S&M , or as a compound initialism from B&D, D&S , and S&M. This type of pornography is almost exclusively hentai, as true hermaphroditic humans are not fertile and are not usually found in nature. These actors often play the top roles but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. Pornography may fall into more than one genre. Rape pornography features performers simulating rape. To avoid soreness from this resulting friction, some may prefer to use a personal lubricant, hentai videos masturbation cream or saliva during masturbation. Bear features a combination of middle-aged, hairy or overweight males. Group sex pornography features at least two men and two women , usually more, who all perform sex acts on each other. It is also known colloquially as gushing or squirting, although these are considered to be different phenomena in some research publications. At the end of the evening the female partners would randomly select keys from the bowl and leave with that key owner. Many cultures describe pain as an aphrodisiac. Most bisexual porn is made by small production companies rather gay bear porn than the major studios.