Bonsai Kitten was a web hoax a few years ago, just google for it. Its originator claimed that he was growing cats inside of glass jars, but in reality they were just pictures of kittens put into glass jars like this cat tried to do (or maybe with their faces shoved up against glass similar to the jar... I don't recall any pictures of a full cat in a jar).
I knew I remembered it from a few years ago. Thanks!