In Portland there is a tile-lined tunnel leading out of downtown where exhaust grime collects. Often there will be "graffiti" on the wall that isn't graffiti at all, but rather someone writing a message by writing in the grime. Things like "Happy Birthday, Brittney" are common. It is a variation of "Wash Me" written on a dirty back windshield.

Now someone is making a business of this. Street Advertising Services uses high-pressure cleaning machines to wash advertisements and logos onto dirty pavements using a client-specified stencil.

The idea was born from a frustration of the founder of trying to find an inexpensive way to advertise in London. The company operates mainly in the UK, but it is open to projects elsewhere. This would be the easiest business to start. I expect it to take off in other markets.

Look for an ad in a tunnel near you!

P.S. Beyond advertising, why not sell standard stencils of reindeer to people for their driveways to deck them out for the holiday season?