If you don't get it, the girl loves the Chicago Cubs, while the guy is wearing a jersey of St. Louis Cardinals First Baseman Albert Pujols. The Cards and Cubbies are huge rivals, maybe the third-biggest rivalry in baseball behind Yankees/Red Sox and Dodgers/Giants. Of course I think the Atlanta Braves/New York Mutts tops 'em all.
Here's the vid the Braves girl (will come up with names soon) was jamming to.
"My fans have more balls." - Tony Stewart on Jeff Gordon's fans.