Apparently the norm in South Korea is to post your cell number in the window of your parked car, since in all probability, your car is blocking someone else’s. They will need to call you to move your car. Used to be the numbers were scribbled notes. But Younghee Jung  has noticed recently that the practice is becoming formal, and now the numbers get fancy print stickers. The numbers in his photos below are scrambled (by him) at the end.

He writes:

...putting owner’s mobile number printed on the front window seems to be on its way to become a norm for car owners in korea. and often its not a scribbled note anymore. the parking convention in korean cities does require leaving the contact information on the car, as people may have no alternative in resting your car without blocking other cars’ exit route, for instance.