Social networking may be fueling revolution across the Arab world, but in Brazil it’s inciting problematically large street parties. The official start of Carnival is just two days away, and street bands called “blocos” have begun their scheduled parades in neighborhoods across Rio. The newspaper O Globo says that schedules passed around on sites like Twitter and Facebook have prompted record crowds for a host of new blocos in posh neighborhoods like Ipanema and Copacabana. One example—after the singer Preta Gil tweeted to promote her parade in Ipanema last Sunday, she estimated that eight times as many revelers showed up this year, compared to last. Here’s a photo. The city government, unprepared for these “flash mobs”, says next year it will move some of the blocos north to the city center.