There’s a new phrase echoing through school hallways — and it’s driving teachers up a wall.

“Six-seven! Six-seven!” is not a math problem. It’s the latest Gen Alpha obsession — and educators across the US (and some in Australia) say it’s gotten so out of hand, they’ve had to ban it from classrooms altogether.

The mysterious slang term comes from the viral song “Doot Doot (6 7)” by rapper Skrilla, which features the endlessly repeated lyric “six-seven.”

The phrase — which can mean nothing, something or whatever you want it to mean — has exploded on TikTok and Instagram, often paired with videos of teens chanting it, dancing or using it as an inside joke no adult seems to understand.

Some say it’s a nod to NBA star LaMelo Ball’s towering 6-foot-7 frame. Others claim it’s shorthand for saying something is “mid” — something that’s average or mediocre.

Elementary school teacher Kaitlyn Biernacki recently posted about how the slang ruined one of her recent math lessons.

As she drew a bar graph on the board, she asked her class “how many votes a cheetah” got. When a few kids shouted “six,” Biernacki dutifully plotted it — only for a chorus of giggles to erupt in the background.

“Six-seven!” some snickered, clearly more interested in TikTok slang than arithmetic. Biernacki shot them a perfectly sassy side-eye that said: Nice try, but this isn’t a meme classroom.

Another TikTok user who identifies as an eighth grade science teacher (@mscollaketeaches) uploaded a funny meme of someone looking annoyed as JoJo’s 2004 hit song “Leave (Get Out)” plays in the background.

White text over the clip reads: “Teachers hearing “6’7″ for the 100000 time after a long day of overstimulation.”

The caption for the video? “No seriously I’m gonna start kicking people out.”

The Post reached out to some of these teachers for comment.

Fourth grade teacher and TikToker Monica Choflet (@mermaid4teaching) says she’s taking matters into her own hands — with a little old-school discipline.

In a recent clip, Choflet vowed to “help with the whole six-seven fiasco” by making her students write out the line: “I will not say ‘6-7’ in class.”

The catch? They have to write it six times for the first offense — and seven times if they do it again.

Gen Alpha isn’t just chanting “6-7” — they’re rewriting the dictionary.

The Cambridge Dictionary recently added some 6,000 new words, including slang that would make any adult scratch their head.

Take “skibidi,” a nonsense word from a viral YouTube cartoon that can mean anything from “cool” to “bad” — or literally nothing at all.

Then there’s “delulu,” the shorthand way of calling someone totally delusional.

Overall, it’s just numbers, kids say — but for teachers, “six-seven” might as well be a new curse word.