Query: "file 13" (throw sth. away)

[sagehen]

>    Today a secretary asked me if I know the origin of "file 13" or "file
>(sth.) in 13,"
>meaning to throw sth. away. I had never heard this expression and asked
>her for an example. She said that if she got sth. of no importance, she
>might say, "Oh, I'll file this in 13," i.e., toss it in the waste-basket.
>Years ago I heard a similar expression: "I'll file it under G" (for
>garbage).

>    Has anyone heard of "file 13" or "file it in 13"? And would anyone
>know why "13" was chosen and not, say, 12?

>    Any help would be much appreciated.

>Gerald Cohen
~~~~~~
I haven't heard this, but the choice of "13" woould seem to be a normal
extension of  superstitions about that number.  Sort of like the
non-exisence of a 13th floor in some buildings: consigning it to oblivion,
like dropping it in the oubliette.
A. Murie