Mall owners began barring them from entering the complexes. So they hung out on the steps. A few scuffles between groups of kids gathered outside drew the attention of the local news media. When reporters came to check things out the floggers directed them to Ms. Vivero, who confidently explained the new movement.

Soon she was making regular appearances on television news and talk shows.

“People don’t understand what this is all about,” she said. “People are used to fame coming from television or from sports but not from the Internet, where people are posting photos and bringing people together and having fun.”

Floggers are not “like hippies or punks, who had ideals of fighting to change the world,” said María José Hooft, who wrote a book, “Tribus Urbanas,” on youth subcultures in Argentina. “Floggers don’t want to change the world. They want to survive, and they want to have the best possible time they can.”

The Cumbio craze really took off after Guillermo Tragant, president of Furia, a marketing company, discovered Ms. Vivero and the floggers last April while scouting for fresh faces for a Nike sportswear campaign. Nike wanted “real people from the streets,” Mr. Tragant said.

“The power of the image for them is so strong,” he said, noting the afternoon “matinee” parties where floggers gather and walk a catwalk posing for photos of one another. “The sensation that the famous floggers are living today is like what Hollywood movie stars experience walking the red carpet.”

THE Nike campaign ran for three months, with Ms. Vivero’s image in sunglasses and a sideways-turned-cap appearing around the country. It included a giant sneaker-shaped slide outside Abasto that the floggers could slide down while posing for pictures.

The Nike modeling led to promotional appearances. Now on most weekends a manager whisks Ms. Vivero around the country to promote discos and to help sponsors sell branded clothes. They pay for the flights and pay for rooms in four-star hotels for her and a small entourage.