Reverse Graffiti

Reverse graffiti also known as clean tagging, dust tagging or grime writing, is a method of creating graffiti on walls or other surfaces by removing dirt from a surface. It is usually done by removing dirt/dust with the fingertip(s) from windows or other dirty surfaces. Reverse graffiti on windows/glass can be highly visible due to the reflection of sunlight. Due to the lack of paint it is often considered legal and used for Advertising,with companies such as Microsoft and Smirnoff, have had their products advertised this way. ~ Courtesy of Wikipedia

That shit would make the Ol' Dirty Bastard proud.

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