I was ranting a couple of weeks ago about this meme dynamic themes. Turns out they're "officialy licensed"! How do you even license such a thing? Do you have to track down the original creator of the image? (specially in case of the rage faces).
Yeah, you can track down the original source of a lot of the memes, but a lot more of them live in a legal grey area where no one is credited with the original image, and so it's fair-use until someone proves they own it.