Trouble on Third Street. Last Friday, during a rehearsal of Teen Spirit’s band, Cool and Unusual Punishment, in Drummer Boy’s apartment, the downstairs neighbors (DNs) called up and told them to cease and desist.

Immediately.

Apparently, the DNs, who were having houseguests, had sent an e-mail to Drummer Boy’s parents that explicitly asked the band not to rehearse over Thanksgiving weekend.

Understandably, the DNs were pissed. The music is cruel and unusual punishment for anyone sitting in his living or dining room.

You’d have to be a saint to live below a drummer (and these nice people seem willing to put up with his daily practice). But the ear-splitting band rehearsals are, quite truthfully, beyond the pale.

Smartmom ran into Drummer Boy’s parents on Third Street. They felt terrible about not reading the DN’s e-mail until it was too late. And now, the DNs don’t want the boys to practice in the apartment anymore. Ever.

Looks like it’s time to find a rehearsal space for the boys. And that spells the end of an era.

The boys have been rehearsing in Drummer Boy’s apartment for almost three years. They even wrote a song called “2L.” The people who used to live in the apartment below were noise-tolerant, rock aficionados.

Only once did they call during a rehearsal. The kids got scared — unnecessarily, it turned out: “Please play ‘Where is my Mind’ again. It’s one of our favorite songs,” one of the DNs said.

Phew.

The Pixies-loving old neighbors moved out and the new ones are not nearly as enamored of the pounding bass, the banging drum, and the migrane-inducing guitar feedback.

You really can’t blame them.

Clearly, Drummer Boy’s parents don’t want to aggravate their neighbors. But they also want to support their son. It’s tough to be the parents of a rock and roller these days.

And, apparently, it’s not all that unusual, either. All over the Slope, kids are forming rock bands. An article in the Styles section of the Times called it the “Kid Core” scene. What seemed merely cute a few years ago isn’t just cute anymore: it’s serious. And these bands — Cool and Unusual Punishment, Fiasco, Care Bears on Fire, Dulaney Banks, Tiny Masters of Today, Hysterics — are talented and career oriented.

“They are developing a following on New York’s burgeoning under-age music circuit, where bands too young for driving licenses have CDs, Web sites and managers,” the Times wrote.

Perhaps the Times should have called them “momagers.”

That phrase was coined by Drummer Boy last year when the moms of Cool and Unusual Punishment helped them organize a Teens for New Orleans benefit concert at the Old Stone House.

The moms (and dads) transported equipment, sold food and tickets, and helped clean up afterwards. They cried during the sad songs and clapped along with the audience during the rowdy ones. They had to force themselves not to get up and dance.

It’s embarrassing enough for their kids that they’re in the audience at all.

Truth is, the parents are as into it as the kids. And why not? The kids are showing real initiative and creativity. They’re developing responsibility, ambition, and even musical chops.

It’s also a perfect retort to that classic Seventh Avenue question, “So what’s your kid up to?” He may not be enrolled at Stuyvesant, a star athlete, or racking up countless social service credits for college apps. But “He’s in a band” surely counts for something.

And among the alt-parent scene in Park Slope, it’s practically a badge of honor to have a kid in a band — especially among parents who wish they’d had the talent (or the kind of parents it takes) to be a successful rock and roller.

In the Slope, well-connected, media-savvy parents are helping their kids big time when it comes to the Big P: Promotion. Care Bears on Fire and Fiasco have already been featured in New York Magazine and the Times. What’s next: The Brooklyn Papers?

Being in a band keeps the kids off of Seventh Avenue on weekend nights when other Slope kids pay off homeless guys to buy them cheap vodka.

And the parents love the music. For the most part, it’s what they grew up on: punk, New Wave, roots rock. Teen Spirit loves to hear Hepcat talk about the Ramones at CBGBs, the Talking Heads at the Mudd Club and the B52s at the Pyramid.

For them, rock and roll is a way to connect — like other fathers and sons use baseball.

So you can imagine that not having a space to rehearse is a big problem for the Cool and Unusual boys. For that matter, it must be problem for many local teen rockers.

Where do all these other bands practice?

If it’s true that a lot of these kids have famous parents (Lucian Buscemi, son of Smartmom’s fave, Steve, is in Fiasco) which means that they probably get to practice in their parent’s brownstone or palatial apartment. Grrr, they don’t have neighbors to worry about.

Really, who’s going to complain to the guy who played a killer in “Fargo” that his kid is making too much noise playing the drums?

But what’s an apartment-dwelling Park Slope teen rocker supposed to do? Dulaney Banks, a local blues guitar and vocal duo, practices in the Ninth Street subway station.

That won’t work for Cool and Unusual Punishment because of Drummer Boy’s kit and Teen Spirit’s bass amp, each of which weighs at least 100 pounds.

Hopefully, Drummer Boy’s parents, a lawyer and a political speechwriter, can negotiate a workable agreement with their downstairs neighbors. Otherwise, the boys will be out looking for another place to practice.

Prospect Park is safer than ever, right?