The warning at the end of this clip, by Purdue University professor Mark French, is "Do not try this at home." Yeah, right.
French and his ME students are demonstrating a de Laval nozzle using a Ping Pong ball. They launch the thing at supersonic speeds and, in so doing, impart enough force to blow a hole through a conventional Ping Pong paddle.
The paper describing their work is here: http://arxiv.org/ftp/arxiv/papers/1301/1301.5188.pdf