Depending on how much American telly you have watched in your life, you may or may not know of Mad Magazine. If not, essentially the only thing worth knowing about it is that it had a regular feature called the 'fold-in'. This consisted of a picture and caption that could be folded in a specific place to show a hidden picture and caption. Often with a sharp satirical edge to the joke. Anyway, the point is, some of them have been put on this here internet and I strongly suggest you take a look-see.