Does anybody know the name of the toy that is a bubble you can ride inside?

I have seen this awesome toy in several magazines and T.V. shows. Basically it is an inflated plastic bubble that you can enter into, and then ride it down a slope/hill - flipping upside down the entire time. Does anybody know the name of this toy?|||its usually called a human sphere....|||Probably what Kidbrainer said, it's probably a human sphere. I've never heard of it, but I think I saw it on a magazine. I don't think there's any other sphere people can roll in. It's sounds fun.