Steve Purcell’s ink drawings for that crucial copy protection code wheel that came in the box of The Secret of Monkey Island - this thing. I still have ours!
What’s better than a piracy prevention device that actually depicts PIRATES? Arrr! I still have this Dial-a-Pirate™, too, along with two of the Mix’n’Mojo wheels from LeChuck’s Revenge. I’ve always appreciated that none of these pirates are in the game (well, not exactly: the dude on the bottom left looks an awful lot like Guybrush, and maybe that’s a proto-Elaine in the top row?), adding a bit of extra unseen character to the game’s world.
See also this great circa 1990 photo that cropped up a few months ago showing the Monkey Island developers personally assembling the Dial-A-Pirate wheels, getting ready to stick them in the retail boxes!