When my son was about 4, I took him to the swimming pool at the local YMCA. In the locker room was a one-legged man getting dressed. He was sitting right next to where my locker was so we had to share the bench.
My son was naturally curious about his missing leg and kept staring at the man. My son’s curiosity made me nervous. The man might not like being scrutinized so closely (though, in hindsight, it was probably no big deal and he might have even enjoyed the wonder in the eyes of a 4-year old).
To distract my son I started chattering away with him as I was dialing the combination to open my lock. The lock was old and cranky and it wouldn’t open on the first try. With absolutely no planning or intention, I blurted out, ‘This lock is on its last leg.’
I could have sank though the floor.