If breaking a mirror brings seven years bad luck, what happens when you break a disco ball?

“Maybe 30 years of bad dancing?” wonders Dianna Petitt, who accidentally shattered one in January. So it’s a good thing no one is watching how well she busts a move every Tuesday night at Dance Dance Party Party. Since the beginning of the year, Petitt and Lauren Houghton have been emceeing the District’s version of the carefree boogie bash, which was developed in Brooklyn in 2006 by two gal pals who wanted to groove but hated the sleazy nightclub scene.

The idea caught on, and now there are 17 chapters of DDPP around the world. The weekly hourlong dance party has only three rules: no booze, no boys and no judgment. Attending a DDPP is like being at the best slumber party ever, minus the pillow fights, crank calls and actual sleeping.

“It’s a nod to something nostalgic that brings your youth back and gives you a sense of community,” says Houghton, who first experienced DDPP while living in London.

Petitt had been a DDPP regular in Boston. She and Houghton experienced withdrawal when they moved to D.C., so they each contacted DDPP headquarters to find out what they could do about it. A DDPP “den mother” put the pair in touch — “We went on a DDPP blind date and hit it off,” Houghton says — and gave them their marching orders.

The first step: Find a cheap venue. Petitt and Houghton secured a multipurpose room at the Park View Recreation Center for free, so they don’t need to charge a cent. The second step: Dance.

Each week, a growing crowd of women of every shape, color, age and outfit (though it’s recommended you wear something you can sweat in) gathers to bop around. Multicolored lights keep spinning all hour, and so do the jams.

“The type of songs you play at weddings are the biggest hits,” Petitt says. “Anything by Whitney Houston is a popular one. And ‘Love Shack.’ People love ‘Love Shack.’ ”

“It’s such a release,” said Silvana

Naguib, 31, after alternating between sassy head tosses, body rolls and a pushup-like maneuver while “Shake Your Groove Thing” blasted at a recent DDPP. “The first time I went, I was walking to the Metro afterwards and my legs were rubbery.”

Many attendees would not be comfortable moving that freely if it weren’t for the all-female environment, Petitt says. They can act silly or sexy and not worry about attracting unwanted attention.

“I was surprised, even in a room full of women, how long it took me to let go and realize that no one cares how I’m dancing,” Petitt adds. “We’re not trying to be exclusive by saying boys aren’t allowed. It just removes one of the stumbling blocks to letting loose.”

For any guys who are feeling left out by DDPP’s policy, Petitt offers this retort: “In order to impress the men, we have to practice our moves somewhere!”

DDPP at the Park View Recreation Center, 693 Otis Place NW; Tuesdays, 7 p.m., free; dancedancepartyparty.com. (Georgia Ave-Petworth)

Boogie Benefits

Dance Dance Party Party is more about letting loose than getting a workout, but there are undeniable health benefits to shaking your butt and keeping your heart rate elevated for an hour.

“One of the greatest things about dance from a fitness perspective is it’s a total body workout,” says Sarah Sands, owner of Dance Trance D.C. (dancetrancefitness.com/dc), a high-intensity choreographed fitness program with classes at two studios in town.

For those who want to treat a dance party as a workout, Sands recommends punching your arms in the air, incorporating jumps and getting low to the ground.

“Particularly during hip-hop songs, squat down and engage those thigh muscles,” Sands says.

The most important thing is that you’re enjoying it, says D.C.-based trainer Laurent Amzallag (yalafitness.com), who created the YaLa workout, which sets choreographed athletic moves to a bumping playlist.

“It gets women moving and they have fun dancing to their favorite songs,” Amzallag says, “and that’s all that matters.”