How long have you known these Cubs fans that you aren't used to their crap yet?
In one of my classes the teacher used to work for the Cubs and he is a big Cubs fan. On the first day he was going over class rules and stuff then he says, "Dress code: The only dress code is that you don't wear Sox stuff." He said this while pointing to a guy wearing a Sox shirt. So being the hardcore Sox fan I am I made a point of wearing a Sox shirt today to spite him and the numerous other Cubs fans in my class. Ahhh, I love being a rebel.