As 3D animation become more life-like, even the most skilled artists struggle to get human movement just right. But what happens when you throw out any attempts at accuracy in the pursuit of the exceptionally bizarre? I'd say this video here does an excellent job of showing the results of such an endeavour.
Creator Mike Pelletier calls this work "Parametric expression"; apparently it's a "study of quantified emotion". I'd describe it as "horror, in polygons" but then, I'm not an artist.
I'd recommend watching the video in full, but if you just want to witness the weirdness, skip to the 45-second mark.
So, what are you seeing exactly? To make them easier to animate, 3D models are almost always "rigged", a process that involves adding invisible bones and joints that can be pulled and twisted. In response, the model dynamically modifies itself to match the changes in position and rotation.
Normally, an animator will apply clamping to these bones, so they can't be moved in such a manner that would make the model look strange or incorrect.
However, if that clamping is removed (or never applied in the first place), then it's simple to distort a model in odd and interesting ways... ways that can make it difficult to sleep at night.