The glans itself may widen and lengthen as the stimulation continues, becoming slightly darker in colour, while the gliding action of the foreskin reduces friction. These actors often play the top roles but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. This gay sex can, however, redirect semen into the bladder . BDSM communities generally welcome anyone with a non-normative streak who identifies with the community; this may include cross-dressers, extreme body mod enthusiasts, animal players, latex or rubber aficionados, and others. However, bisexual pornography is often placed near the gay section in adult video stores, since many consumers are gay men. Content featuring male bisexuality has been a growing trend since the advent of internet pornography. Transsexual porn star Wendy Williams has stated that transsexual Porn is classified as Straight Specialty. The act may be carried out face to face, or head to tail, with the woman recommended to be on top if she has smaller breasts. This stop and go build-up, known as edging, can achieve even stronger orgasms. Arcane or occult pornography involves sexualized situations with an occult or magical tone or performers who costume themselves in keeping with the theme, for example, a male performer dressed as a wizard. There is, however, no third party camera work involved. Stimulating the prostate from outside, via pressure on the perineum, can be pleasurable as well. Most bisexual porn is made by small production companies rather than the major studios. There are number of types of sex parties: Swinger party/gathering A swinger party or partner-swapping party is a gathering at which individuals or couples in a committed relationship can engage in sexual activities with others as a recreational or social activity. Incest itself is largely taboo, and is a crime in many countries. The term pearl necklace is used by some because the drops of semen deposited by the man resemble a necklace of translucent white pearls.