Social Distortion
I saw them at the old UCSD gymnasium in '90 when I was in 10th grade. One of my first concerts, my friend Jon insisted that we go (in his parents' minivan!). We only knew them from Social Distortion so I was just blown away by the old school punks, the pit, and the white-hot fury from the band.

I saw them at the O'Brien Pavilion in Del Mar in December, 91. The bill was Red Hot Chili Peppers, Nirvana, Pearl Jam. Amazingly, there's actual footage up on YouTube: