?

How do you lose a shoe walking down the sidewalk and not notice? I just walked to the gym and there was a high heeled shoe under the tree. This isn´t the first single shoe that I´ve seen on the street and it´s always baffled me. Where is the other shoe? Did your shoe just fall off and you couldn´t be bothered to pick it up so you kept walking? Did a dog attack you and all that´s left is a shoe? I mean, what´s the scenario here?