Used as a verb, when someone angrily or aggressively yells at, screams on or insults you as if their mouth were a gun and their words were bullets. The leading cause of arguments turning into physical altercations especially in public.
"We fired shots at each other back and forth on mixtapes but when I saw him at the mall suddenly it was just music."
"The waitress at Red Lobster smiled at me and my girl just started firing on her automatically! Man I had to pull her up outta there."
"I ain't for the games today bo, I'ma fire on the first person who even look at me stupid!"