From 1903 to 1905 a unique comic strip was published in the New York Herald: you would read the first half, then flip the page upside down to read the second half.
Gustave Verbeek’s The Upside Downs of Little Lady Lovekins and Old Man Muffaroo was brilliantly experimental in its use of the comic form. At first glance, it looked like a standard newspaper comic strip. Look a little closer, though, and you notice that each panel has two captions: one below and one above and upside down.
After having read the first set of panels, the story continued by physically turning the page upside down and reading an all-new set of panels. The second set used the same art (often cleverly hiding a completely different scene, as with the panel above) but with new captions to narrate the action.
The comic itself featured two characters, the grizzled moustachioed Old Man Muffaroo and the rather suspiciously wild-haired Lady Lovekins. The moustache of the former turned into the hair of the latter, of course. The comic used very few speech bubbles, but when they were employed the text could be read both ways, like an ambigram. Brilliant.