A ball crusher, also called a ball clamp, is used to apply pressure to the man 's testicles . In some cases the toy can be tightened with the help of a wing nut. Other models are stretchy and enclose the balls tightly when the toy is attached. A ball clamp, as it were, seizes the man 's masculinity . For this reason it is a popular toy in bondage play. This involves a certain power relationship, in which one dominates someone and the other takes on a submissive role.