If you’re going to put something in file 13, is it headed to a) a top-secret folder, b) a Christmas stocking, or c) trash can? It’s the trash! This term first became popular in the 1940s during WWII as military slang, and by the late 60s had fully entered civilian speech. Other jocular expressions for the same thing include round file, circular file, or file 17. This is part of a complete episode.