Road markings are very important, but since you know that they'll always be there and they'll never change, these signs sometimes take a backseat to flashy advertisements. However, Japan's Fukuoka Prefecture implemented a new road signage system that makes its messages more grabby.
With extremely narrow roads expected to hold two lanes of cars as well as pedestrians, these unconventional road markings were put in place to encourage drivers to go slower. The ads stretch out vertically along the length of the road and convey slightly scary, but to-the-point messages like "AH! DANGER!" and "Things will jump out at you!" If text like this doesn't get a driver to be more cautious on dangerous roads, I'm not sure what will.