Letter 35 https://learnitalletter.substack.com/p/letter-35-from-a-learn-it-all

Cockamamie: A foolish or ridiculous person; or a decal, a design that can be transferred to a surface.

It came from earlier than 1940–45, Americanism; in its original sense, “paper strip with an image which could be transferred to the skin when wet,” as an alteration of a decal; the current sense “ridiculous” probably by association with cock-and-bull story or poppycock.

The etymology of cockamamie: Although the word was adopted by Jewish immigrants earlier in the 1940s in New York City to refer to transferable decals, it comes from French décalcomania. Cockamamie (or cockamamy) is now used to describe something wacky or ridiculous. It's often heard among those familiar with Yiddish.

Example using the word: Of all the cockamamy excuses I ever heard, my Resistance said I couldn’t film my video tonight because the dogs needed my attention.