Sometimes “street artists” are fine artists gone wild, having fled the sterile confines of the gallery to apply their work directly on the urban landscape.

Sometimes they are graffiti artists who have outgrown writing and rewriting their own names. The canvas in both cases is the same—walls, tunnels, bridges, street signs, or most any other stretch of drab concrete that is technically private property but actually up for grabs. The best known of them all is Shepard Fairey’s OBEY campaign, a series of stickers and posters that presented wrestler André the Giant, his fictional “posse,” and the word “Obey” in Soviet propaganda style. Over the last ten years, Fairey’s project has grown from a few Rhode Island art school students to Fortune 500 clients willing to pay the Obey team handsomely for advertising work done in their trademark style. That’s the trouble with many street artists—too often the message is “look at me,” “here’s a joke you don’t get,” or even worse, “I’m for hire.” The best street artists have the power to change the pedestrian experience of the city, like Swoon, who humanizes blank walls with life-sized posters of children at play. Street art is at its best when it’s humorous, novel, mysterious, and coy. When it comes with its own excessively theoretical online manifesto, it can get annoying pretty quickly.

For Example: Banksy

Bristol-based street artist Banksy began humbly, making anti-authoritarian stencils, but soon raised his sights to the global stage, covertly installing his own paintings into prominent museums in London and New York and painting ladders and holes onto the side of the Israeli West Bank barrier wall. His first U.S. art show, in Los Angeles, featured a live painted elephant and reaped more than $1 million in sales. That’s a lot of cash to spend on his next stunt.

Here's a tip: The ol' smile and wave.

If some passerby catches you red-handed, don't let them know it. Pretend you're official. You'll be surprised how often they play along with you. Remember, it's guilt that gives you away.

Risk: 4
Cost: 5
P.R.: 7
Cred: 6

Coolness Factor: 6.5