I remember a poem or verse about it. It is a rural, older couple arguing
about who's going to get up and bar the door. I seem to remember the
main refrain is the man saying to the woman, "Katie, bar the door!"
While interesting, I don't think this is relevant to the primary use of the
expression. I'm not knowledgeable about country music, but I get the
sense that there's a long tradition of country songs that take a familiar
phrase and give it a twist...