A friend just sent this. They call this guy (Robert Muraine) "Mr Fantastic" after the rubber-limbed comic-book hero in the Fantastic Four. Here's a clip of his entry on "So You Think You Can Dance".
I used to have what's called hyper-mobile joints (before I got old and still) - I could easily get my elbows well past each other behind my back, do full splits, get my feet behind my head, and so on.
But this is in a whole 'nother world.