Know this about Irving Bierman.

The Brooklyn native’s been a New York Knicks fan for 63 years, he’s fed up with the team’s lousy record this season and — despite the wishes of the team’s owner — there’s no way he’s rooting for the Nets.

“You’ve got to be kidding me,” the 73-year-old diehard said of switching loyalties. “It’s irrelevant to my universe. It’s not the way that I am.”

For the last few days, the Carolina Forest resident has been the talk of the sports world because of his email exchange with Knicks owner James Dolan.

After Bierman sent Dolan a critical message late last month, the owner fired back an angry response, telling the passionate septuagenarian to “start rooting for the Nets because the Knicks don’t want you.”