There's an ad I've seen several times about the internet, advertising tape worms for use in dieting.
This image can easily be found googling "tapeworm diet ad". Snopes asserts uncertainty as to whether this is real, but I'm not sure if that's authoritative.
What I find particularly interesting is that one of my professors whose focus is history asserted near certainty that this ad is fake, because the fonts and styles used in this ad are anachronistic and don't make sense together. I don't know enough to know if that's credible; anyone have insight?