Hype fidelity? John Cusack confronted at Game 3 by Barstool Chicago personality telling actor he can’t be fan of Cubs and Sox

There’s an unwritten rule in cities with two sports teams of the same game:

You can’t possibly be a fan of both teams.

If you’re a Chicago Cubs fan, then rooting for the Chicago White Sox, now heading into Game 4 of the American League Division Series against the Houston Astros, would be akin to treason.

At least, that’s how Barstool Chicago apparently sees it. A video posted to Twitter Sunday shows Barstool employee Dave Williams confronting Evanston-born actor and noted Cubs fan John Cusack at the game about breaking this unwritten rule.

But instead of hiding his face, Cusack claps back. “You can’t tell me who to root for,” he tells Williams. “I can root for whoever I want.”

In the video, Williams accuses the actor of “jumping on the White Sox bandwagon,” but Cusack shows off his White Sox trivia, quizzing Williams — who claims not to know some answers because he’s too young to know some of the answers.

“That just proves your ignorance,” said Cusack, who wore a White Sox uniform in “Eight Men Out,” the 1988 film about the 1919 World Series scandal.

Williams further protests, claiming, “half the fun about being a fan is being miserable. You can’t just go to the Cubs side,” adding that it’s “against the rules.”

“We’ll just have to agree to disagree,” Cusack concedes before giving the man a fist bump and walking away. Williams makes a retching noise and tells viewers that “John Cusack is banned.”

Some Twitter responders suggested it was Williams who was out of his league.

At least one Twitter user agreed with Williams’ “bandwagon-hopping” remark.

This wouldn’t be the first time Cusack has been vocal about his love for both teams. While cheering at a Cubs game in June 2008, the actor insisted that he supported both teams — and he rattled off what a Chicago Sun-Times reporter called “old statistics and obscure players from White Sox teams past to prove it.”

“I grew up watching both teams,” Cusack said. “I love the Sox as much as the Cubs. I get in a lot of trouble for it, but I remember when Mike Squires and Lamar Johnson were platooning at first base” for the Sox in the late 1970s and early 1980s.

Cusack’s duel allegiance also upset White Sox owner Jerry Reinsdorf during the team’s 2005 World Series run, but the two managed to patch things up.

“I played [George] Buck Weaver in ‘Eight Men Out,’ so I wore the colors of the Sox,” Cusack said. “I really do love them.”

After this encounter, Williams might want to stick to the on-field action during Game 4.