Kiss My Ass Charlie, You're On Your Own. Called over your shoulder when abandoning a dumbass who insists on doing something stupid or illegal (usu. both) against your advice. Said dumbass is often the fucktard who hangs, uninvited, on the fringe of your group of friends.
Scott observed Dick scratching stick figures having buttsex into the church pew, and noticed that Sister Helen was coming down the aisle. He whispered, "KMACYOYO," and moved to the next row.