OK, so this one is not forró.
Samba rock is a style of dance very particular to São Paulo, especially the outer districts of the city. It’s been an important dance for the past 5-6 decades in family parties, and has recently made the move into dance schools and larger events in the city. If you’re in São Paulo, you should never miss a chance to dance and listen to samba rock.
The best event by far is this one, in a neighborhood called Casa Verde. World-famous Clube de Balanço plays, typically on the third Sunday of every month. It’s advertised to start at 16:00, but much more likely to get rolling at about 19:00.