For some people, a transcutaneous electrical nerve stimulation (TENS) machine is used as an alternative to painkilling medication. A TENS machine is a small portable, battery-operated device which is worn on the body. The box is attached by wires to sticky pads stuck to the skin. Small electrical pulses are transmitted to the body, like little electric shocks. This can help to ease pain in some people with certain types of pain. These guys are using the TENS machine for a different purpose.