There can be few in the new world who have not heard of madcap, crazy - call him what you will - Rolf Harris.
Standing at the giant canvas with decorators roller in hand, gracious Rolf would draw what seemed a random doodle of squiggles and suchlike, often interluding the genius at work with his catchphrase: Can you see what it is yet? That was television back in the seventies.
Unfortunately, to my untrained eye, I never could see anything, well not until Rolf administered his final flourish and somewhat miraculously a work of artistic grandeur would reveal itself, amazingly completely hidden only a few seconds and roller strokes prior.
Of course, looking back, it was an act of supreme delusion. Rolf had craftily constructed his routine in that very manner, planning and plotting exactly how to administer those final touches in order to provide the maximum of entertainment and suspense to us, the watching viewers.
Order from chaos.
For more on "hidden messages", please see this