Italian are born to be humorous. In many cities I visited, the traffic signs were changed a little bit. You can see the creativity of the people there. Unlike graffiti, I feel this modification of public property is humorous, decent, and not offensive. It even can be designed as standard signs to demonstrate the characters of the country. Enjoy some of them.
Below: Smiling Pedestrian This Way.
Below: Leonardo da Vinci not Allowed
Below: Heart Broken Road on the Left. 
Below: STOP! I am Working Hard!
Angels Turn Right; Devils Go Ahead!
Signs like this are spread out all cross the country, from Milano to Roma.