Solo performances in gay pornography have been described in 1985 as either or both active and/or passive , whereas female solo performances are said to be exclusively passive . They may be noted for using risqué themes, graphic violence, sexuality or black comedy in a manner that is unsuitable for younger audiences. Bondage pornography specializes in the depiction of sexual bondage or BDSM activities as photographs, stories, movies, or drawings. Some pornographic films use an artificial semen substitute to simulate or enhance creampie shots. Breast fetishism is a paraphilic sexual interest focused on female breasts . Barebacking usually refers to a conscious and deliberate choice to forgo condoms. Its gain in prominence has been attributed to its depiction in the film Pecker, which was released in 1998. It is milf xxx geared towards heterosexual men, who most typically define a threesome as such. Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face. Works in this genre may explore philosophical, political or social issues. Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses . Snowballing or snowdropping is the human sexual practice in which one person takes someone else semen into his or her mouth and then passes it to the mouth of the other, usually through kissing. Testosterone discourages fat storage in these areas. The term pearl necklace is used by some because the drops of semen deposited by the man resemble a necklace of translucent white pearls. Both sexes sometimes apply lubricating substances to intensify sensation. Studies among BDSM gay twink porn practitioners in the US have shown that about half of all men find the idea gay hentai of bondage to be erotic; many women do as well. They signal the presence of estrogen and the presence of sufficient fat stores for pregnancy and lactation. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place.