It is almost easy to create a supersonic ping-pong ball. All you need to do is to understand some physics, like the pressure created by air over a vacuum chamber, use pressurized air, packing tape, a convergent-divergent nozzle and a plastic tube and voila, you got the ping-pong cannon.
Mark French, professor at Purdue University, was able to set the stage for this special cannot that fired the ping-pong ball with about 1.2Mach. To test how dangerous such a hit is they used a paddle as an obstacle and the ball simply flew right through it. You got to love physics