Hydraulic torture - predicament bondage

A male slave is tightly bound in a chair. An inflatable butt plug is first inserted.

The male slave is fitted with a condom catheter which drains to a reservoir on the floor. Every couple of hours a pump on a timer empties the floor reservoir into an enema bag on a pole behind the chair.

The enema bag is, of course, plumbed to the butt plug.

So over time the inflatable plug begins to fill. Eventually the sub will try desperately not to pee so the plug stops growing. And once they have to let go it's just a matter of time before the plug gets even larger.

Rinse and repeat.