Trent and Amy Sheridan are about to find out.
Amy, who grew up in Milwaukee, has been a huge Packers fan, even volunteering at Lambeau Field while in college. Trent, who grew up in Chicago Heights, used to travel to Platteville for the Bears training camp.
Their team loyalty even surfaced on their wedding day, when they sported a cheese head and bear claw.
"I brought my laptop into the wedding and were able to stream the game and watch it during the reception," admits Amy.
It surfaced again last weekend when Amy went to great lengths to watch the Packers playoff game.
Through the years, the two have attended many Bears-Packers games together and spent a lot of time trash-talking.
"I would say the in-laws jab a little bit more than I do. I think what I found out is at some point there's a final whistle the end of the game and I have to go home and I have to see her outside the environment, so I kind of skate that line of appropriate and obnoxious," said Trent.
Now the two will have to decide how to handle Sunday's game.
"When the Bears won on Sunday, I said maybe we shouldn't watch it together. I think the range of emotions that'll go on during the game might get us in trouble, or at least me in trouble," according to Trent.
"It might be better if we don't. One of us is going to be unhappy on Monday," she said.
Despite Sunday's outcome at Soldier Field, the two will have to tackle the rivalry again come July, when their first child is due, and they have to decide if he or she will follow their mother or father's team.