This is a bit of fun, that’s all. It is, obviously, not really a headless cat. Charlie, the black cat (brown cat?) in this picture has three legs. When he is grooming, which he has a habit of doing to a slightly obsessive level, he can look like this:
I have a feeling only a three-legged cat can look like this because the right foreleg would normally be visible in this picture which would have made him look less like a round ball of brown/black fur.
The flash light has shown us how brown a black cat is. It does not take much to show up the dark brown eumelanin pigmentation granules in the fur that makes a cat black. Black fur is almost a visual illusion as the pigment is not black at all.
I am pleased to say that Charlie is pretty flexible and can wash all the usual accessible places of his body.