Group sex is sexual behavior involving more than two participants. Sex experts have praised various techniques that the performer can use during fellatio to increase their partner pleasure. A sub-set of vaginal fisting attempts to photograph the female cervix immediately after the fist is removed from the now-gaping vagina. Sexologist Alfred Kind suggested that the buttocks is the primary sexual presentation site in primates. Unlike erotic films, pornographic films contain explicit sexuality and do not claim any artistic merit. Sex parties may be organized to enable people to engage in casual sexual activity or for swinging couples or people interested in group sex to meet, but any gathering where sexual activity is anticipated can be called a sex party. This category also includes pornographic home lesbian milfs movies. Especially popular in post-World War 2 Japanese culture. It may be used as foreplay, or as an alternative to sexual penetration. Another variant of reality pornography consists of normal couples that are filmed by professionals, in which case the only obvious distinction from amateur pornography is the higher quality of production, filming and editing. Said that the female buttocks evolved in the context of females competing for the attention and parental commitment of powerful resource-controlling males as an honest display of fat reserves that could not be confused with another type of tissue, although T. In the context of consensual erotic activities, sadism and masochism are not strictly accurate terms; there is a significant difference from the medical or psychological usage of both terms. Fisting pornography features the insertion of an entire hand into a performer vagina or anus. Rough sex pornography young gay porn is similar to pornography featuring sadomasochism, and typically features a Top anime hentai who humiliates and/or degrades a Bottom while being physically violent towards them. Shemale is a term primarily used in sex work to describe a trans woman with male genitalia combined with female secondary sex characteristics, usually including augmented female breasts, from breast augmentation and/or use of hormones.