in california state prisons who ever has the keys of there race is the shot caller. or man in charge of his people. it derives from the act when your race wars with another race, or rides. when you ride, your at war.
also in california state prisons, there are basically 4 races that stick with each other... whites, southsiders (mexicans), northern mexicans, and blacks. each race is called a car, hence if your calling shots your driving the car, hence you need the keys to drive.
an inmate that might roll up on the yard and ask a fellow inmate "hey who's got the keys here"?