Well, dogs also do this—I present to you my majestically twisted creature: https://imgur.com/a/5WcYzSw

I have no clue how that is even possible.

Brought memories of one of my cats (now silent meow) who also added the Italian equivalent of a middle finger.

https://imgur.com/a/GFukfFP

Your dog is the inverse of the Firefox.

I almost sprayed all my tea to my monitor and keyboard.

Wish both of you a happy and derpy life together.

Clearly your dog has been possessed by a demon.

Dog Yoga

Doga.

I'm also stupefied by a human doing it. https://imgur.com/a/W7bcLZo

Taken from: https://www.gq.com/story/aleksei-goloborodko-real-life-diet

Yeah, nope. If I get like that, I'm never coming back. Probably have to bury me in that pose.

Is this really just a matter of stretching? I read the article and he sums it down to he needs to stretch every day (he said himself thst his diet doesn't matter too much) He was also in the circus since 4, but this doesn't seems like something I could do in a lifetime of practice.

You probably couldn't. There are lots of forms of hyper mobility, and extreme versions come with health risks. With practice and training you can probably do a lot more than you imagine, but for most of us the whole "fold yourself in half backwards" thing is beyond the limits of our spine, and it's for the best.

No, it's not just down to stretching although I remember being told that as a kid when asking about "snake ladies" in circuses. Yes, the stretching and training is necessary but all the stretching and training in the world won't help you bend like this. Some people simply have hypermobilities (often from connective tissue disorders) and these can allow them to bend themselves into a pretzel. The stretching and training is as much for learning how to take it to such extremes as it is for learning how to do it (relatively) safely. Of course these conditions can still often lead to complications and often have other negative impacts like chronic pain, frequent bruising, slower healing and a tendency to dislocate various joints.

majestic indeed!

My Shiba Inu does all kinds of similar things. He also doesn't hesitate at all when trying narrow spaces. He only hesitates once he's all the way in and realize he can't go any further nor turn around so he has to back up completely back out.

Mine managed to fit into this tiny basket, all by himself: https://i.imgur.com/htIw6ZV.jpeg