Gray bandana gang related

There Are Neumerous Gangs That Rep black flags depending on what set your in and where you come from.

Gangs that rep black falgs:

Folk

other "Folk Nation based gangs" comming from the deep south

Panthers

some crips (depending on region)

some bloods (depending on region)

GD gangs(Gangster Disciples)

BGD(black gangster Disciples)

"Black Flag Crew"

these are just all the ones i know of so depending on where you come from this may vary

i hope this answer was real enough for the person that wanted to know unlike some made up story to scare people