For legal reasons, the vast majority of so-called reality porn involves professional actors and actresses posing as so-called amateurs. Such ejaculation can be done by mammary intercourse, or masturbation over the other person, or result from the withdrawal of the penis from a partner mouth as he is ejaculating following fellatio, irrumatio, or intercourse. 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. Some may keep their hand stationary while pumping into it with pelvic thrusts in order to simulate the motions of sexual intercourse. Transsexual pornography is a genre of pornography. Once insertion is complete, the fingers are either clenched into a mature milfs fist or kept straight. The name was coined from the title of the controversial book. The genres of pornography are based on the type of activity featured and the category of participants, for example mateur pornography is a category of pornography that features models, actors or non-professionals performing without pay, or actors for whom this material is their only paid modeling work. Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses . The other person may do the same during or after. Originating in Japan in the 1980s, the genre subsequently spread to North America and Europe, and crossed over into gay pornography. Women who perform in lesbian hentai sex pornography often do not consider themselves lesbian or bisexual. Types of anal gay twinks sex can also be a part of lesbian sexual practices. Bukkake is a sex act portrayed in pornographic films, in which several men ejaculate on a woman, or another man. Some straight actors have started acting in gay porn only to be accused of being gay while others first step was to strictly do solo scenes. The phrase is commonly found on porn sites. Sadomasochism is practiced in isolation relatively rarely, though some masochists report biting, pinching, or even stun-gunning themselves as a prelude to, or as part of, masturbation.