First heard it by George Thorogood, and it sounds like a bastardization of the word “concern”, but was that the way it was commonly used when “One Bourbon, One Scotch and One Beer” was written?
Not really - the original (John Lee Hooker?) blues version was much shorter. Later versions of the song, including Thorogood’s, included the additional dialogue with the “landlady” but that was not part of the original.
My grown-men-boys use the word “conversate” for talking with other people. At first I hated it. Now I like it and would use it myself, but that would make them immediately drop it from their vocabulary.