This genre also features male-on-male fellatio through a small hole made in a bathroom divider. 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. Mutual masturbation, mutual manual stimulation of the genitals between partners, can be a substitute for sexual penetration. John Stagliano is considered to have started the gonzo pornography genre with his Buttman series of films. The queening stool is also related to a smotherbox, which also allows the person under the seat to be locked lesbian milfs in place, restrained by the neck as in a set of stocks. The activity is done by itself or as a part of or prelude to other activities which many times involve sex. 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. Once insertion is complete, the fingers are either clenched into a fist or kept straight. Foot fetishism has been defined as a pronounced sexual interest in the feet or footwear. Bestiality is illegal in many countries. Bukkake pornography involves a performer, usually female, onto whom several men or women ejaculate, usually on the face. Pro-am pornography is sub-genre of amateur pornography that refers to professionally made porn that features amateur actors/actresses, often appearing for the first time in a pornographic film. Examples of mentally oriented practices are education games, during which the dominant requires certain forms of behavior from the submissive. Following the introduction of the Motion Picture Association of America film rating system, independent animation producers attempted to establish an alternative to mainstream animation. A related term used in the genre is the lesbian hentai term cougar, which implies an older woman as predator. Men may also rub or massage videos porno gay the glans, the rim of the glans, and the frenular delta. Mammary intercourse is known as titty-fucking, titfuck, or a titjob in the United States, as well as tit wank or French fuck in the United Kingdom - the latter term dating back to the 1930s; while a more jocular equivalent is a trip down mammary lane.