We decided with the help of a special stencil and sponge to put on dirty cars that are in the car wash, our advertising message (like a jokers, who often write different funny phrases on dirty cars): "This is a 10% discount on car wash at Nekrasov, 112-A. The owners of cars didn't erased the message because it was their discount. Therefore, on the way to wash the car becomes a free advertising medium.

Summary and results: Because the message was left on the car on arrival at the car wash, we were able to track the number of successful contacts, and thus assess the effectiveness of the campaign. 60% of visitors came to our car wash on the message board. Attendance increased by 3 times.