At the annual Battle of the Bands at UC Davis, Kelly left the Tree costume on the bus after a long day in the sun, and Cal students broke into the bus and stole the costume. The following week, the band received a ransom note offering the Tree in exchange for Oski the Bear (which had been stolen from the UCB Student Union the year before). The band did not think this trade was worth it. The tradition of building a new costume was born and every year since then, the Band and their many admirers now expect the Tree to be reinvented every fall. With more exposure, the decision about who would become Tree became more rigorous, and the band had to adopt a more formal selection process. Today's Tree candidate must go through "grueling and humiliating physical and mental challenges" to show that he or she has sufficient chutzpah to be the Tree. During "Tree Week," candidates have been known to perform outrageous, unwise, and often dangerous stunts in order to impress the Tree selection committee, so much so that the university has felt the need to prohibit certain types of audition activities over the years. The Tree's costume, which is created anew each year by the incumbent Tree, is a prominent target for pranksters from rival schools, in particular from Stanford's Bay Area nemesis, the University of California, Berkeley (Cal). This tendency for the Tree to come to harm at the hands of Cal fans was showcased in the run-up to the 1998 Big Game. An anonymous coterie of fraternity brothers from Cal known as the Phoenix Five stole the costume and held it "hostage" for two weeks until it was turned in to the UC Berkeley chancellor's office and returned to Stanford by the UC Police. In 1996 two Cal students emerged shirtless from the stands at Memorial Stadium at the Big Game during halftime and tackled the tree, breaking branches and eliciting cheers from the Cal alumni prior to being handcuffed and led away. The most recent theft of the Tree was during the 2012 basketball game against Cal, when a member of the Cal Band entered LSJUMB's bus and removed the mascot. Older bandsmen quickly sent the Tree outfit back that evening and no charges were pressed. Violence and absurd levels of prankery have been a two-way street between Cal and Stanford. A few