I did this! In a post on Mastodon a while back I suggested the idea for a QR code which simply decodes to the text “Please do not scan this QR code again.” It’s a reference to a joke in Hitch-Hiker’s Guide to the Galaxy in which a character in a spaceship cockpit presses a button which does nothing except cause a sign to light up which says “Please do not press this button again.”

A fedi friend saw my post and actually made a shirt with the code (with my blessing) and I bought one, along with a sticker for my laptop.

(Anyone else who wishes to use this idea for anything, go forth freely. I claim no ownership.)