The students had announced:

"Stripping down to their skivvies, students at UC schools will be protesting sweatshop-made UC collegiate apparel. Bearing the slogan: “We tried to find sweat-free clothes in our bookstore and this is what we came out with” (i.e. nothing), students hope to highlight the widespread practice of producing collegiate apparel in factories with poor labor standards, said Kate StormoGipson a UC San Diego student activist affiliated with the nation wide student organization United Students Against Sweatshops (USAS)..."

http://www.indybay.org/news/2006/03/1805519.php

The spirited UC Santa Cruz protest was one of six planned in the UC system - the others being Berkeley, Santa Barbara, San Diego, Davis, and Riverside.