Bear features a combination of middle-aged, hairy or overweight males. A related term used in the genre is the term cougar, which implies an older woman as predator. Though there have been numerous gang bang pornographic films since the 1980s, they usually involved no more than half a dozen to a dozen men. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. Some are aroused from wetting their diapers, others like messing their diapers. In general, BDSM play is usually structured such that it is possible for the consenting partner to withdraw his or her consent during a scene; for example, by using a safeword that was agreed on in advance. These actors often play the top roles but this is not always the case, such as with Kristen Bjorn and some Bel Ami models. Many transgender people regard the term shemale as offensive, arguing that it mocks or shows a lack of respect towards the gender identity and gay sex video gender expression of transgender lesbian hentai individuals; in this view, the term emphasizes the biological sex of a person and neglects their gender. Group sex pornography features at least two men and two women , usually more, who all perform sex acts on each other. The niche popularity grew significantly in the latter half of the first decade of the 2000s. Sexual orientation Pornography features an increasing variety of combinations of actors by their sexual orientation such as lesbian, gay, bisexual, and transsexuals in addition to traditional heterosexual roles. Hermaphrodite, also known as herm, refers to pornography, typically hentai, that features persons with the genitalia of both sexes. Such ejaculation can be done by mammary intercourse, or masturbation over the other person, or result from momporn the withdrawal of the penis from a partner mouth as he is ejaculating following fellatio, irrumatio, or intercourse. In the gay pornography industry, which uses amateurs as well as professional actors, the term gay-for-pay refers to actors labeled or believed to be straight but who engage in same-sex sexual activities for money.