Last week, in the industrial heart of Downtown L.A., thousands of people were confronted with art and artists behaving badly. Big time. Graffiti and litter messed up every square inch of the walls and grounds around the crowds. But judging from their body language and smiles, the people were having the time of their life. And who could blame them?

For several weeks, dozens of artists from around the world have been working hard inside and outside of the once gritty old garage building which, a quarter of a century ago, was transformed by Frank Gehry into what is known today as MOCA's Geffen Contemporary. The resulting exhibition, with its messy, explosive, joyful energy, is called Art in the Streets.

If you had the misfortune of riding the New York subways in the late '70s or early '80s, you might be excused for your grudginess toward graffiti. And the same can be said for regular folks feeling abused by taggers scrawling their names around local stores and apartment buildings. And again, who could blame them?

But what a difference 30 years makes ... And that is precisely what this museum exhibition is all about. Without art behaving badly we would have never had the thrill of discovering the graffiti art of Keith Haring. And can anyone enjoy the great paintings of Jean-Michel Basquiat without feeling and smelling the danger of the streets that inspired them? Or would Barrack Obama's presidential campaign be the same without the Shepard Fairey posters pasted all over the country?

One wants to congratulate MOCA's director Jeffrey Deitch, who has been able to pull this wild rabbit of an exhibition out of his hat, in spite of the embarrassment caused by the white washing of the mural that initiated this exhibition a few months ago.