There is also some evidence that pornography can be used to treat voyeurism. In D/S, the Dominant is the Top and the submissive is the Bottom. It can also be heightened by the person saying that they have to urinate. Fisting pornography features the insertion of an entire hand into a performer vagina or anus. Since at least 1973, it has also been used to refer to a sexually attractive young woman. Fetish cuckolding can have a wide range of expression, from pillow-talk fantasy between monogamous partners to extreme alternative lifestyles, depending on the couple. Going back at least as far as the Christy twins in the 1970s, depictions of incest and particularly incest between twins has been a feature of gay pornography. Japanese rope bondage is distinguished by its use of specific katas and aesthetic rules. Practitioners have described going to public places such as a mall or a park. Social attitudes towards the discussion and presentation of sexuality has become more tolerant and legal definitions of obscenity have become more limited, leading to an industry for the production and consumption of pornography in the latter half of the 20th century. Strictly speaking, bondage means binding the partner by tying their appendages together; for example, by the use of handcuffs or by lashing their arms to an object. Solo pornography features performers masturbating. Bondage is usually, but not always, a sexual practice. They may repeat this cycle multiple times. Foot fetishism, foot partialism, foot worship, or podophilia is a pronounced sexual interest in feet. Reality Reality pornography refers to real porno gay or faked amateur encounters. Other forms of anal sex include fingering, the use of sex toys for anal penetration, oral sex performed on the anus , and pegging. Human urinal: An act common in the bondage sex community where a male or female slave will serve as a urinal for a dominant partner. As with most forms of sexual activity, anal sex participants risk contracting sexually transmitted infections .