Humans have been hula hooping for hundreds of years. During the first half of the 20th century, the best way to see someone use a hula hoop was to watch Chinese acrobats twirl multiple hoops on their arms, legs and torsos. Then, in 1958, Wham-O toy company founders Richard Knerr and Arthur "Spud" Melin saw the potential in the humble hoop and began to mass-market a 40-in. version made of colorful plastic tubing. Thanks to a savvy marketing campaign, 25 million hoops were sold within a few months of the product's launch; the hula hoop craze was off and looping, with kids all over America spinning hoops around their hips and waists. Hula hooping teens became an iconic image of the 1950s, and the fad grew when Wham-O began manufacturing a smaller version of the hoop for the younger set. While the hula hoop never went away, it has had a bit of a revival in the past five years with popular hoop fitness classes. You can even hire a personal hula hoop trainer.