From Wikipedia page, note "a" on the bottom:
I am here to learn, and so thanks for the heads up from lakevin out in California!
"The alternate name "Southern Cal" frequently appears in sports-related news articles. USC discourages use of "Southern Cal" out of concern the name might suggest a foundational association to the University of California, Berkeley (commonly known as "Cal" in the athletics context), even though the two institutions have no affiliation other than their Pac-12 membership. For several years, USC's media guides contained the following request: "Note to the media: In editorial references to athletic teams of the University of Southern California, the following are preferred: USC, Southern California, So. California, Troy and Trojans for men's or women's teams, and Women of Troy for women's teams. PLEASE do not use Southern Cal (it's like calling San Francisco 'Frisco' or North Carolina 'North Car.'). The usage of 'Southern Cal' on licensed apparel and merchandise is limited in scope and necessary to protect federal trademark rights..."