"What the [bleep] is Sean Penn doing on the main stage of Coachella?" asked the actor-activist to the crowd gathered at the 2008 Coachella Valley Music and Arts Festival - the three-day indie rock celebration held this weekend in Indio, California.

Penn was there Sunday to recruit festivalgoers for his six-day Dirty Hands Caravan, which will make a round trip to New Orleans and back on a fleet of biodiesel buses, spreading a multi-layered message of voting, volunteerism, political activism and continuing the post-Katrina clean-up in New Orleans.

"We got buses right here at Coachella. We'll feed you and take care of lodging at no cost to you. We'll leave at 1 p.m. tomorrow from the clock tower." Musicians Ben Harper and Everlast will provide entertainment along the route.

The 47-year-old Oscar winner went on to tell the crowd, most of them under 30, that "revolution is a young man's job, and you can be the revolutionaries."

He then ended his plea quoting Spicoli, his stoner character from "Fast Times at Ridgemont High." "I'm going to say something I haven't said in 27 years. Hey bud, let's party!'"

- Denise Quan, CNN Entertainment Producer