Say what you want about Mr. Met — but you better not insult his momma.

The ball-headed Mets mascot flipped off fans at Wednesday night’s game after he was forced to his “breaking point” by a crowd of hecklers hurling nasty comments about his mother, a witness told The Post.

The wisecracks hit a nerve for the team employee wearing the costume, since he has been having trouble with his actual mom, the source said.

“The fans were cursing at Mr. Met with the F-word and saying derogatory things about Mr. Met’s mom . . . which led to the gesture because of a personal matter with his mom,” the source said.

“It triggered something that recently happened. It was his breaking point.”

The jeers caused the Amazins’ mascot to lose his cool moments after the team’s 7-1 defeat to the Brewers at Citi Field.

As Mr. Met headed down a tunnel to the interior of the stadium, he turned and gave fans a one-finger salute, which was captured on a video that went viral Wednesday night.

Tony De Lucia, the fan who recorded Mr. Met’s gesture, insisted he was not saying anything derogatory.

“I did nothing to provoke it. I had my phone out to record getting a high-five,” he said. “If it was directed towards other fans or others’ actions I am not sure, but I did not say or do anything to provoke Mr. Met, nor did I say or do anything before, during or after the video to provoke him.”

Different people don the Mr. Met costume depending on the day, and the team has not said who was wearing it when Mr. Met flipped the bird.

The team issued an apology Wednesday, calling the scene “inappropriate” and pledging to deal with it internally, but it has not decided whether to fire or reassign the offending actor, officials said.

Mr. Met returned to the field Thursday — albeit with a different person inside the suit, according to team officials.

But the mascot has already struck out with fans, who say the foul gesture disgraced the team.

“What a schmuck. In this day and age — with everybody having a camera in their hands,” griped Bill Curreri, who co-authored the memoir “The Original Mr. Met Remembers” with founding Mr. Met Dan Reilly.

“It’s really disappointing because Mr. Met is there for the kids,” said Leslie Perez-Bennie, 35, of Queens. “Our son loves Mr. Met. [The mascot] has to remember he’s a kids’ character.”

Former mascots were more forgiving than fans.

“It was definitely inappropriate and unprofessional, but I feel for the guy,” said John Dunphy, who wore the costume from 2012-2014. “If the team is performing poorly, [fans] go after you — you are this giant mascot and you are a target . I’m sure Mr. Met has taken a lot of abuse.”

Additional reporting by Kevin Fasick and Katherine Parker