Shades of Silly Boyhood Toys
I was pretty excited when I saw this link for Swingbike because we played with one of these when I was a 13 and 14. My pal Arby had one, or his little brother did, and we had a blast riding it sideways with the front wheel on one side and the rear wheel on the other side of a bar or log or whatever.
It didn't go very fast and wasn't very comfortable to ride but it was still fun to play around on.

And now the bugging things are becoming collectors items.
That and I think I'm going to have to get my hands on one of these Phat bikes.