If you see an empty car parked with its headlights on, chances are the car will be locked. This is not an applcation of Murphy's Law, but rather an aspect of human kindness. If the car had not been locked, someone, seeing the car before you did, would have reached in and turned the lights off.
I was thinking of this recently, when I returned to my totally unlocked car to find I'd left the headlights on. Everybody, where were you?