To fire a gun, usually at someone.
Refers to the fact that guns fire when the trigger is pulled and causes a firing pin to literally "pop" an explosive cap attached to the end of a bullet, causing
the bullet to
spiral out of the grooved
barrel at tremendous speed.
The
rap artist stated that he would pop a cap into another rap artist, but we all know that the state would never grant him a
concealed carry license due to his convictions for multiple felonies, so he'll have to purchase a firearm through
the black market.