I had one of these, and I must respectfully disagree with the submitter about their inherent danger.

but what do they call it

http://www.poetv.com/video.php?vid=35413

We got one ot these at the goodwill back when I was a kid. I always wondered what the story was.

Pogo Bal sounds like some lesser Aztec deity

Finally, a device to help me jump half as high as I normally can!

I think I had one of these too, but it wasn't fun enough to use until I broke my wrists.

We always had at least one these things around during recess in elementary school. It would inevitably be completely deflated.