On Tuesdays, I have a chronic memory failure about what I am supposed to do on the way home from work so, as a joke, a co-worker stuck a Post-it to the front of my beanie that said "Get fuel, pick up books". I wore it for a while and then the joke wore off so I took it off. "Somehow" the note got reattached but I didn't notice.
It was only as I was entering the servo to pay for my fuel and I got a very strange look (and giggles and pointing!) from some customers coming out of the store that I realised that the note was still attached to my hat - I have driven all the way down to the servo, filled up my car and then walked across the really quite large forecourt with the damn thing stuck to my head!