What is "gang signal"

n. A gang sign.

A gang signal is a visual or verbal way gang members identify their affiliation. This can take many forms including slogans, tattoos, hand signs and colored clothing. Many of these, especially slogans and hand signs, have become part of popular culture. The wearer usually favors, or is in, that particular gang. With symbols, graffiti is a large symbol displayed on walls or trains.