When Jed York and the San Francisco 49ers announced the partnership with Levi Strauss for the naming rights to the team's new stadium in early May the nickname jokes flew hard and fast. York quipped that the best one he heard was "Field of Jeans." "Big Button Fly" and "The Big Zipper" were others suggested by the deluge of the late-night comedian want-to-bes. While we were all joking, Levi apparently was taking notes. The jean company applied for a trademark on the "Field of Jeans" phrase, Mike Rosenberg of the San Jose Mercury News reported this week.