Short for a"'thats what you get' smack". A good, hard backhand to the back of the face which was well deserved, usually by cheating on a boyfriend/girlfriend.
Man: "Baby I'm sorry I slept with your sister."
Woman smacks the hell out of Man
Woman: "That was a getsmack, bitch."
Woman smacks the hell out of Man
Woman: "That was a getsmack, bitch."
by Zuke July 12, 2006