Starting tomorrow, an activist t-shirt brand will do its best to, er, drum up some attention in Dolores Park by asking passersby to sign an oil barrel with messages that will be delivered to BP at the end of the month.

Dubbed the Bang the Drum tour, the campaign from United We Fit, whose signature t-shirts for men and women include the letters “UN” and blank space for the wearer to fill in with words of his or her choice, aims to raise continued awareness about the oil spill and send a message from consumers to BP.

The tour organized by the Texas-based fashion brand kicked off in New York on July 2 and has since stopped in Los Angeles. Over the weekend, the tour heads east to Berkeley, where it will continue to gather signatures and messages during the Michael Franti and Spearhead concert. The last stop on the tour is Houston, home to BP’s U.S. headquarters.

Want to send your message to BP? Find the drum in Dolores Park tomorrow and Friday from 10 a.m. to 3 p.m.