Gordon Spitzmesser’s “combustible gas-powered pogo stick,” patented in 1960, is exactly what it sounds like: a pogo stick with an internal combustion engine.
“In using this device, the cycle is started by the operator giving the initial jump upon the foot rest. As the frame reaches the bottom of its stroke, thus causing ignition of the sparkplug, the resulting compression forces the ball valve to seat and remain seated during the compression stroke of the piston and until it passes the exhaust ports in the manner described. The instant that the cylinder is cleared, new air and gas is permitted to enter into the cylinder, thus enabling the cycle to be repeated.”
All of this, we are told, is “extremely safe and harmless and of tremendous entertainment value.” You go first.