However, the term "gat" is actually an old term. It dates back to the late 19th Century when it became a shortened name for the Gatling Gun. As it evolved, it became a term used for all kinds of guns. Who used it best? In my opinion, Humphrey Bogart used it best. Watch this great video from the gangster movie "The King of the Underworld" (1938). Around 50 second into this video is where you want to look.