Well, I hate the rails way of overloading hashes for options, but it is a way to do it...

If you are going to use this, you should do several things:
* recognize this is not intention-revealing and provide some documentation
* handle the case where your default options are used, either by making the default options something like "backs_red" or gracefully handle the empty hash in a programmer friendly way

An alternate would be to have a card_image(rank = [your favorite rank], suit = [your favorite suit]) method and a card_back_image(color = 'red') method... or some magic CSS that turns data attributes into an image.