Reverse Graffiti

This guerilla ad campaign in Chicago is made with a stencil and a pressure washer. Kind of the high-tech version of writing on a dirty windshield with your finger.

It reminds me of when I was around 15 and Mom called out "who's the wise guy who wrote 'clean me' on the buffet?" Even without fingerprint technology I got nailed for it and, though it wasn't my turn, I had to dust the living room and dining room.