"Don't go to the supermarket directly after running a marathon, with a virtually empty stomach. You may pick up a basket, put your wallet (and keys) in it, decide you want a cart, put the basket back and then not realize your wallet was in it until you go to check out. Thankfully it was locked up at the Customer Service desk, intact. " - who do you think?
I blame glycogen depletion. That's my story and I'm sticking to it.