I put them in a standing copper pipe predicament, a predicament because the pipes are wired, ready and willing to dispense the harsh sting of electricity. The pipes are an integral part of their bondage, so there's no way they can avoid being shocked.
Each of their respective asses are also outfitted with metal hooks that, of course, put out a shocking punishment in addition to the pipes. Their sphincters contract on my discretion, and with the copper pipe predicament, their punishment and pleasure are entirely at my discretion.