Who hasn't? I was on my way to work one time when I decided to make a quick stop at an office building to see someone for a minute. When I entered the elevator car keys somehow slipped out of my hand and went down the slot between the floor and the elevator floor. I managed to retrieve them and not be too late for work.
'Nother time I went to a store then back home -what!! no keys in my pocket. Retraced my route back to the store and there they were on the floor at the foot of the counter. Must have came out with the coins when I dug into my pocket and slipped out of my hand unnoticed.