Hee hee, someone I know has said his cousins used to try to throw another cousin's shoe out the window when they were in the car on road trips, and sometimes it would happen on somewhere like an exit ramp where their parents thought it was too dangerous to go back and get it!

I have also seen people set a pair of shoes on the roof of their car while they opened the door and forget them there and drive off - usually "dress shoes" and they're wearing sneakers ... so I am betting both shoes ended up at the side of the road, but maybe around different corners!