Jenna Bush Hager reveals her personal habit that left late grandmother Barbara Bush horrified

Jenna Bush Hager detailed how her late grandmother — first lady Barbara Bush — once called her out in a letter for unsportsmanlike conduct.

“I’m competitive, and I like performance around competition,” the anchor said on Thursday’s episode of “Today with Jenna & Sheinelle.”

During a family tennis match, Bush Hager, 44, was “doing the worm and yelling, ‘Not today!’”

At the time, the anchor was a “full adult.”

Bush Hager admitted, “I like to heckle, OK?”

“My dad, [former president George W. Bush], thought it was very funny and he’d be like, ‘That’s my girl!’”

While the journalist’s father, 79, was amused, both her late grandmother and late grandfather — former President George H.W. Bush — were not.

Bush Hanger didn’t exactly heckle her grandparents, but they weren’t thrilled by what they witnessed either.

“My grandfather really believed in sportsmanship, like being really kind and humble and all those things,” she recalled to co-host Sheinelle Jones, 48. “And I think my … behavior rubbed my grandmother the wrong way, so she wrote me a letter.”

When Bush Hager returned from summer vacation and was gearing up for her three kids — Mila, 13, Poppy, 10, Hal, 6 — to return to school, she received her grandmother’s note.

“The best part is that she addressed it to me and my dad,” the author said. “She was like, ‘That behavior on the tennis court was not becoming. And George, you shouldn’t have cheered her on, either.’”

The former first lady, meanwhile, didn’t want anyone to know about her note.

Bush Hager elaborated, “And then it said, ‘P.S. Throw this letter away and don’t tell anybody about it.’”

As the NBC anchor cheekily stated, “Oops!”

Bush Hager has never shied away from airing her hilarious family stories while live on air.

Last month, the reporter, who tied the knot with husband Henry Chase Hager in 2008, revealed the offensive nickname her children have given her.

“They call me Biggie,” she confessed to Jones. “They’re like, ‘OK, Biggie!’ And I’m like, ‘Excuse me?’ They’re like, ‘Whatever, Biggie!’”

The TV personality asked her eldest to cut it out, worried that her younger kids would use the moniker in the wrong setting.

“I’m like, ‘Mila, stop saying this. Hal’s gonna go to school and his teacher’s gonna be like, ‘Now, Hal, please turn in your homework.’ And he’s gonna be like, ‘No way, Biggie!’”

She explained that the term “Biggie” hails from “Big Back.”

“She has simplified it just to Biggie. Part of me at first found it to be … I like humor in words, so I was like, ‘Oh, that’s creative,’” the media mogul detailed.

“But I’m like, ‘Stop calling everybody Biggie. It’s gonna spread,’” she quipped.