Any ideas on how this funny sort of "stuttering" in early blues developed? It seems to have been popular.
https://books.google.ie/books?id=zvTq5DNtn9MC&pg=PA56&lpg=PA56&dq=if+river+whiskey+was+mallard+duck&source=bl&ots=wZKcXmTOvU&sig
E.g.
"I've got the blues but I'm too mean to, I said mean to, I mean cry."
Or

"if the river was whiskey and I was a mallard , I said a mallard , I mean duck "