A woman can use a secondary vibrator, between the dildo and her genitals, to get pleasure from pegging. A study of the condom usage habits of New Zealand black milfs sex workers said that they offered various safe sex alternatives to vaginal sex to clients who refused to wear a condom. Some people get sexual pleasure by inserting objects, such as urethral sounds, into the urethra , a practice known as urethral play or sounding. Contrary to the other two types, B/D does not define the Tops and Bottoms itself, and is used to describe the general activities with either partner being the receiver and the giver. Sadomasochism refers to the aspects of BDSM surrounding the exchange of physical or emotional pain. Diaper fetishism, nappy fetishism or diaperism, is a sexual fetish in which a person feels a desire to wear or use diapers. The resulting consent and understanding is occasionally summarized in a written contract, which is an agreement of what can and cannot take place. Often other friends and community members may witness the signing of such a document in a ceremony, and so parties violating their agreement can result in loss of face, respect or status with their friends in the community. In recent years, however, many celebrities have benefited from the publicity resulting from the release of a sex tape. The preference could be barefoot, high-heels, flip flops, and so on, depending on the fetishist. Typically features adult, masculine men with varying degrees of muscle, body fat, and body hair, akin to beefcakes, or bears. This genre also features male-on-male fellatio through a small hole made in a bathroom divider. Bear features a combination of middle-aged, hairy or overweight males. Sadism describes sexual pleasure derived by inflicting pain, degradation, humiliation on another person or causing another person to suffer. Some anthropologists and sociobiologists believe that breast fetishism derives from the breasts similarity to buttocks, but instead provide sexual attraction from the front of the body.