Worst thing that ever happened regarding key displacement: Had a complicated day planned with my GF, both basically rushing off in opposite directions and doing our things. She forgot something though and rushed back in. When trying to leave again just about 10 seconds later, she couldn't find the key she just used!

We were both searching, no success. Had to make the day work with just one key for both of us. The key was found weeks later in the middle under the bed, covered by other things and dust.

Best theory: They fell on the tip of her shoe while she was walking and got catapulted, kept sliding under things that were already there. But we'll never know.