A type of graffiti-writing style present in San Francisco; namely, the San Francisco public transportation system. It is the act of tagging with a particular style on a San Francisco Muni Bus that blends with the pulse of the bus ride. It's not called Bus Flow for no reason; you gotta have rhythm. Takes a lot of practice and hard work to master. Very illegal as graffiti is a form of vandalism.
by SF Muni March 14, 2010
by SF.SF.SF March 20, 2010