@electronicmail,
electronicmail wrote: "Whistling Dixie" is kind of code for whistling in the dark while walking through a graveyard and hoping to God nothing evil your way comes.
You ain't just whistlin' Dixie: "You're not just talking or making small talk, you're saying something important, worthwhile. 'Dixie' refers to the popular song."
Source: "Whistlin' Dixie", Hendrickson, Robert: A Dictionary of Southern Expressions, New York, 1993