A catheter is a thin tube used in medical procedures for several applications. In the context of BDSM, catheters usually refer to a urinary catheter – a flexible rubber tube that is inserted up through the urethra and into the bladder, draining the urine from the bladder as part of medical play or watersports. Catheters can be a turn on for some due to the lack of control over a body function (urination), which can be a form of submission and humiliation. There are also those who describe the sensation of having a catheter inserted into their urethra as pleasurable.
Using a catheter requires a sound knowledge of anatomy, as well as proper training, to prevent the possibility of causing harm to the body. If the person that’s having the catheter inserted into them complains of pain or discomfort, it could be a sign that you’ve done something wrong. You should also always adhere to strict sterilization, and never re-use catheters.