"We have kids who won't leave," Melnick said. "We had a two-week program with three-hour sessions in the morning and three-hour sessions in the afternoon and they'd play all day."
Long popular at Jewish summer camps, GaGa is now appealing to a wider audience.
For the uninitiated, GaGa is a little like dodgeball. It's played in a confined space known as "the pit"; in South Jersey GaGa's case, that's an octagon shaped by plastic, waist-high barriers. The aim is to get control of the ball - usually smaller and softer than a regular dodgeball - and, using only one hand, hit the other players below the knees. (Some places play below the waist.) Those who are hit are out until the next game. Games typically last five minutes.
"It's Jewish mothers' dodgeball," said Melnick, who noted that his neighbors recently had a GaGa pit installed in their backyard. "No one's going to get hit in the face and no one's trying to hurt anyone."
But unlike dodgeball, which tends to favor the bigger, more athletic players - remember cowering in the corner of the gym right before a red ball came in contact with your nose at 50 m.p.h.? - anyone can win at GaGa, Baselice said. "You can play 10 games and have 10 different winners," he said. "That's appealing for kids."
GaGa is believed to have originated in Israel in the 1960s, Melnick said, and came to the United States by way of Israeli counselors who introduced it to overnight campers. Many GaGa-ites think "ga" is a Hebrew word meaning "hit" or "punch," but in fact, it's a nonsense word - same as in English.
Indoor GaGa facilities are few and far between. Besides South Jersey's, inside the Israeli Krav Maga training center, there are two unaffiliated GaGa sites in New York.
Since Lou Candel, co-owner of Ultimate GaGa on Long Island, opened his doors in 2008, he said he's seen steady growth, including a 30 percent increase in participants since last year. While the business caters primarily to children, Ultimate GaGa has hosted adult parties and corporate events.
"We've started to penetrate towns and areas that didn't know GaGa," said Candel, who was introduced to the game by his GaGa-addicted 11-year-old son. "The challenge is when people hear about us, they think, 'Oh, is it a Lady Gaga kind of place?' "
Wrong Gaga. (Although it's unknown if she's a fan.)
GaGa is good exercise and teaches strategy techniques and builds skills like hand-eye coordination, said Douglas Mann, a Rowan University professor in the health and exercise science department who has written about the benefits of GaGa.
"It's very appealing to our low-attention-span kids because it's a very fast-moving game and games typically don't take very long," he said. "When they're out, they can sit and watch and cheer and still be part of the activity, then there's a new game and a new dynamic."
Chris Guertin, president and owner of Minnesota's Sport Resource Group, started selling GaGa pits - basically, the plastic walls that snap together to form an octagon or other desired shape - in 2008. The number of pits sold has easily doubled each year since. Last year, the company installed 185 GaGa pits, mainly in schools.
"Not everyone can afford to build a new playground, which can be $30,000 or $40,000, and a GaGa pit is less than $5,000," Guertin said. "Everyone's crunched for space. The typical GaGa pit is 626 square feet and a basketball court is 5,000, but you can put twice as many kids in" a GaGa pit.
Jodi Berman of Cherry Hill said her 6-year-old son, Avi, started playing GaGa at camp and fell in love with it. She brings him to South Jersey GaGa almost weekly.
"The game is simple and quick and they're able to play it immediately at such a young age," she said. "No coaches, no screaming, no teams, just simple group fun."
Tara Pal Keenan said her 7-year-old son, Sach, is a cautious boy and GaGa builds his confidence.
"He's won some games but even if he's second or third, he's happy. This is a big deal to him," the Moorestown resident said. "We want to keep him active and this is a safe way to do it."