Double Jointed Cats?

Can a cat be double or triple jointed?

Growing up I had 4 cats, so I have been around them my whole life.

My girlfriend and I adopted a cat about 6 months ago and we really think he is at least double jointed. I know cats are very flexible, but he does things on a regular basis that I never see cats do. First off, he is super long and is like a worm. He can wiggle and slide right through your arms in seconds. Somehow he manages to arm crawl under the couch and dresser. The couch in only 2 and 3/4 inches off the ground and the dresser is 3 inches. Considering my fist is a tight fit between the couch and the floor, I have no clue how he gets under there.

Then there is this pose. His back bent at almost a 90 degree angle. He does this daily to groom himself, or just hang out in the hall way and look at your. It is the oddest thing to just walk into a room and see him like that. Our friends think its hilarous.

From the pictures alone, it doesnt look unusual.
I looked it up, and it seems no body (or cat) is double jointed, they are simply very very limber

Double jointed is just a terminology for a joint that hyperextends, but in animals it usually refers to the the rear leg joints, or hocks, not the spine, but I suppose it's possible. It is usually genetic and not too uncommon in some breeds of dogs. Where two leg bones fit together, the one is not "hollowed out" enough to encase the other bone very well, so the joint bends too far.

My regular vet thinks that my cat has at least one, maybe both, hyperextending hock joints, but the specialist, without looking beyond X-rays thinks it is torn ligaments. His reason was, "because it's too far in the back pages of the textbook for cats to be likely." Anyway it's not a good thing either way.

The younger cats are, the more flexible they seem to be. How old is your cat?