Oh, art school humour.
This one really got away from me.
Of course, the comic is in reference to Escher’s Relativity (1953). It’s a perfect example of intention outweighing the joke. Escher was a genius. I went cross-eyed trying to figure this one out, and I still didn’t come close. On the bright side, at this rate, I’ll never be indicted for forgery. If you want to see what this one should really look like, there is a really fantastic gallery of Escher’s work on the official homepage.