Comic books often featured characters being tied up and tying others up, particularly in damsel in distress plots. Performers are usually clean-shaven, thinner and more effeminate than ones in mainstream gay pornography. A homosexual threesome would involve either three men or three women. Jerk off instruction features a performer encouraging or instructing the viewer to masturbate, often culminating in a countdown at the end of which the viewer is invited to induce orgasm. While bondage is a very popular variation within the larger field of BDSM, it is nevertheless sometimes differentiated from the rest of this field. The prostate gland is one of the organs that contributes fluid to semen. It is mutual consent that makes a clear legal and ethical distinction between BDSM and such crimes as sexual assault or domestic violence. Some BDSM practitioners prefer a code of behavior that differs from SSC and is described as risk aware consensual kink , indicating a preference for a style in which the individual responsibility mature milfs of the involved parties is emphasized more strongly, with each participant being responsible for his hentai sex or her own well-being. The term discipline describes psychological restraining, with the use of rules and punishment to control overt behavior. Incest pornography can feature actual relatives, but the main type of this pornography simply uses actors of similar looks to suggest family relationship. The consent and compliance for a sadomasochistic situation can be granted only by people who can judge the potential results. Advocates of RACK argue that SSC can hamper discussion of risk because no activity is truly safe, and that discussion of even low-risk possibilities is necessary for truly informed consent. This stop and go build-up, known as edging, can achieve even stronger orgasms. There were also a very limited number gay cock of specialist fetish magazines which featured images of bondage, such as the famous Bizarre magazine published from 1946 to 1959 by the pioneering fetish photographer John Willie, and ENEG Exotique magazine, published 1956-1959.