Not sure if relevant but I decided to search for "Garbage File" and google spit this out at the top:
https://en.wikipedia.org/wiki/File_13
"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). Many Unix-like operating systems have a similar reference known as /dev/null. 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." [1]
The first known 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. Another explanation refers to the fact that there are 12 months in the year, and a file is typically kept for each, with the 13th file being non-existent (the garbage can). An explanation given in the NZ military is based on the use of stencil lettering, where a capital B (as used for 'bin') looks like a 13. Or the possibility that trash cans were 13 inches by 13 inches in size.
Another explanation is that the 13th filing cabinet is usually the one which contains the shredder.