According to Jim

Jim is horrified when he sees his son Kyle with a green Packers ball. He tries by all means to change it for a Bears one, but the kid just can't let go of the green ball. Jim has nightmares about it and takes Kyle to his work in another attempt to get rid of the Packers ball. When he realizes there's nothing he can do about it, he does a little alteration on the ball so they can go to the Bears game peacefully.