I always wondered how many of the images on eBay were actually clandestine underworld spy messages. The equivalent of the crossword puzzles during WW2. Ok probably not many but you never know. :)
When the Internet was fast enough, image forums were such a novelty it was common to hoard images/memes/wallpapers for later use. I've always wondered what kind of stenographic messages I unknowingly saved in my old files.