In 1873, C. M. Coolidge painted a series of dogs playing poker. They have been reprinted on posters, calenders, post cards, mousepads, cigar tins and just about every other product under the sun. Most of the pictures have a hidden joke if you look at them hard enough. For instance, in one of the more popular paintings one dog is holding an ace in his paw under the table. He has the most chips.