I like how, if you hold the phone at a distance, but not as far as intended by the font, your brain sort of mixes letters from both messages.

I was at some point reading SAPPY ROMAN, HARPY ROBAN etc.

Also, viewing the "hidden message" works even better if you hold the screen at an angle, tilted away from you.

Also works if you scale/zoom the image. The crisp lines disappear entirely at a certain point.