As we walked towards the canyon, we were passed by a line of VW beetles. We looked at each other and shrugged. We were soon to find out ... about the El Potrero Custom Car Show. Actually, we heard it before we saw it. The music ranged from an elongated boooom to mariachi. Almost every car had it's stereo blasting. Maybe it was a sound contest instead of a car show? There were some pretty wild customizations for a sound contest though, as evidenced by this and this.
Eventually, we made it to mini super wall and did a few easier 1 pitch routes to get a feel for the area. The melange of music didn't take long to drive us back out of the park. It was beer o'clock anyway.