A few years ago, they had some guy throw out the first pitch. He walked out to the Mound with a Cubs' jersey on.
He then tore off the Cubs' jersey revealing a White Sox jersey, pulled a Sox hat from his back pocket and threw the first pitch.
Ever since, the Cubs check out the clothing of the person tossing out the first pitch.
IIRC, he was a friend of a WSIer.
All hail The Rick