If by any chance you happen to be employed at a car dealership / service center, you can (and should) put this to your "must-do" list of things to check and complete: always make sure that a parked vehicle is in gear (manual gearbox) or in Park (automatic transmission) and that the handbrake has been pulled all the way up.
What is that you say; "who cares about handbrakes, they're only useful around corners and on the move"? Sure, you can choose to not listen, but don't come back saying we didn't warn you when you fall in the same pickle as this young gentleman from Moscow, Russia.
He did none of the above and look at what happened to him; he almost got killed when an Audi A3 came falling down from a lift...
Luckily, he lived to tell the embarrassing tale to his boss and the unfortunate owner of the car.