File 13

File 13 refers to a trash can. The phrase is especially used in the U.S. military, and is less common outside the United States. In the United Kingdom, for instance, the expression "round file" or "circular" is more common. 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." The first citation of "File 13" was in 1941. The phrase's origins may perhaps be traced to 13 being a supposedly unlucky number, although the exact source is unknown. According to Slangsearch: Air Force, "File 13" refers to an aircraft's garbage can.

Reference

• File 13, The Phrase Finder.
• Slangsearch: Air Force.