"black as Caesar's tail"

[Lee Murrah]

When I was growing up in East Texas in the 1950s, when something was
very dirty, my mother would say it was as "black as Caesar's tail."
I have searched for an explanation of the term but have never found a
single reference to it.  In that time and place one might suspect
that it had some racial overtones, but I never heard it used in that
sense.  Does anyone have an information on its origins?

------------------------------------------------------------
The American Dialect Society - http://www.americandialect.org