Roy G. Biv
A three-eyed alien questions why humans memorize the visible colors of the rainbow but not the rest of the electromagnetic spectrum.
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Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2017-12-12-roy-g-biv/ (CC BY-NC 4.0)Transcript
Human: "Don't you know 'Roy G. Biv'?" Alien: "No. What's that?" Human: "It's a mnemonic! For remembering the colors of the rainbow."
Alien: "But that only covers the electromagnetic radiation that you can see. What about the rest, like UV and gamma rays?" Human: "Uh... we don't have a mnemonic for that." Alien: "So you take pains to memorize a thing you can see with your eyes, but specifically exclude the aspects that you cannot?"
Human: "Well, when you put it that way, humans sound kind of irrational..." Alien: "On my homeworld, my friends think I made you all up."