According to Jim Recap: The Packer Ball
Kyle is growing up, and Cheryl gets him his first football. Unfortunately, it's a Packers ball, a grave mistake when you live in Bears country, and the mistake is made even worse when you live with Jim. He tries everything to get Kyle to give up the ball, even going down to the vending machine and dropping in 72 quarters to get a Bears ball, but Kyle wants the green one. It looks like a lost cause.
Then he comes up with a brainstorm. Jim and Andy take Kyle down to the office and let the guys tell him all about the greatest year in Bears history - the 1985 season, complete with pictures and the Super Bowl Shuffle.
At the end of it all, Kyle throws his green ball, and it looks like Jim may be in the clear. One of the guys takes the green ball outside and torches it. But while he's gone, Jim tries to give Kyle the blue ball. Let's just say that it doesn't work.
Being the good dad that he is, Jim goes down to the sporting goods store and buys Kyle a new green ball to replace the one that was destroyed. This gets him into a fight, but in the end he does what is right for his son, and that's what matters. When he comes out, a vision of his older son (once again played by Robert Belushi, his real-life son) talks to him and thanks him for sticking up for him.
