Why would anyone do this* to a cat? Note to humans who think they're funny -- there's a reason all the cats in these pictures look ticked off.
We do not exist for your pleasure. You exist for ours.
I also don't find this particularly funny, even though it's fake. But I do think it's kind of funny so many humans thought it was real. There was even a petition to stop the bonsai kitten madness! Silly, silly humans. It's called Photoshop.
*Thanks to Bruce for the link.