Go Pack Go!

It's not too difficult to brainwash a 3 year into rooting for Daddy's team ( the packers ) instead of Mommy's team ( the steelers ) You just need to explain it to them in their terms:

The Packers are called that because they love to pack their backpacks....just like Dora.

The Steelers are called that because the love to steal...just like Swiper the Fox.

With that simple logic, I have an instant Packers fan!