On the "down" side, most people point to the apparent lip on the steps; few staircases would have a surface like that for people to step on. Noted one commenter, "Look at the cat’s tail — it ...

9gag.com Spotted on The Daily Mail, the 9Gag post asks readers if the cat is walking up or down the stairs. At the time of this post, almost 4,000 comments have been made arguing about the image.

We rounded up optical illusions that involve two of our favorite things: cats and dogs. From a two-headed dog to a bird-cat, see how many of these stump you.