In BDSM play, a catheter most often refers to the Foley catheter used for insertion into the bladder. Medical suppliers have many other kinds of catheters that are not normally used by the kinky. The catheter once inserted into the bladder allows the top complete control over the bottom's urination. Care must be taken during insertion of the catheter in order to prevent infection. They are also used during long-term bondage play to allow urine to be conveniently managed.