Definitely done the drive side crank on the wrong side before, and that was after I figured out a bottom bracket issue for that same friend just a minute earlier.

Icy Hot cream and some Sensodyne toothpaste tubes look nearly identical and are the same size. The Icy Hot made it onto my toothbrush and I stopped just short of my mouth (disaster) wondering why the texture was off... It was time to go to bed. And get a new toothbrush...