The birth of hula hoop set off a nationwide "shaking" craze. The people who spread this fanaticism to the world are Arthur Moline and Richard Nu. In addition to being big friends together, they are alumni of the University of Southern California. The prototype of this plastic ring that shook the world was the wooden ring they used when they saw local people exercising in a fitness class in Australia. After a local friend taught them how to shake their hips to make that thing spin, they immediately came up with the idea of inventing hula hoop. They gave their simple plastic rings to children in primary schools to play with, and soon this simple invention entered thousands of households in the United States. We can't predict how long the vitality of the hula hoop will last, but as long as people still use it to shake their bodies briskly, the happy magic of this circle will last.