On a similar but unrelated note, it was only about 12 months ago that I realised that "Piece of mind" wasn't actually piece but peace of mind, I'd often wondered, piece of mind🤔, WTF does that mean🤷🏻♂️, like, yep, this little bit of my mind is ok. It had genuinely never occurred to me that it was actually peace of mind.
I considered myself reasonably sharp and "On the ball" up until that moment. I'm slowly recovering my self esteem though🙄😂.