Gangs use hand signs to identify their memberships and to antagonize other gangs. The Greater Salt Lake Metro Gang Unit refers to this behavior as throwing signs or flashing signs. Sometimes a member identifies a rival member by throwing the rival's sign, then throws his own sign as a challenge.
Gangs use their hands and fingers to form symbols, letters and numbers. The Chicago Gangs website provides links to more than 60 gangs in Chicago and photographs of their hand signs to help the public identify them as of 2015. Rival gangs are offended by each other's hand signs, which leads to hostility and fighting, according to the Douglas County Sheriff's Office.