When someone buys a hoop from me, one of the things I warn them about is that little kids don't seem to "see" a spinning hoop. They'll just walk right up, and into, a spinning hoop. (Cute & LUCKY!) case in point.
The light, plastic kid's hoops that are commercially available don't do much damage, but my heavier, adult-sized ones can cause a bruise or two. So, be carefully, everyone! A kid will look you in the eye as you're waist hooping and walk right into your hoop!