Trey was born in Conifer, Colorado, on October 19, 1969 to Randy (a geologist) and Sharon (an insurance broker). He has an older sister, Shelley. The South Park legend began when he met Matt Stone (co-creator of South Park) while attending the University of Colorado in Boulder, where he had a double major of music and Japanese. He was kicked out of UCB because he was too busy writing, directing and starring in 'Cannibal: The Musical!' to attend classes. He and Stone were asked by then FoxLab executive Brian Graden to produce an animated Christmas card for his friends and family. The now infamous short, titled The Spirit of Christmas (1995), led to "South Park" (1997). He and Matt Stone recently signed a contract in 2007 to continue with South Park for at least a 15th season.