File 13 is a euphemism for the trash can. The phrase is especially used in the U.S. military, and is less common outside of the United States. In the United Kingdom, for instance, the expression round file or circular file is more common (in reference to trash cans typically being round). Expressions such as "I'll place that memo in file 13" are often heard in offices as a joking way of saying, "I'm going to throw away that memo."