Welcome To My Lair
There is nothing more enjoyable than finding your pets in compromising positions. As long as they are safe, there is something funny about finding our animal friends doing things that make them slightly less animal-like and perhaps more human-like.
Or in this case, more alien-like because we have never seen a human-like creature that looks anything quite like this. To be fair, this cat is just staring at a mirror in a funny way, therefore creating this optical illusion. But still, we like to think that an alien possessed this little cat.