>When you spend two hours tearing the house apart for something you misplaced (usually keys) and you realise you've had them in your hand the whole time.... <

I have actually done this only realising after I had shut the front door behind me, only with me someone was on his way to sort it out. After realising my error and knowing there was no time to let the person know I popped the keys through the letterbox to pretend the keys had slipped out of my hand on the way out. Quite quick thinking for an old un?