Verb
whistle Dixie (third-person singular simple present whistles Dixie, present participle whistling Dixie, simple past and past participle whistled Dixie)
(idiomatic, Southern US) To engage in idle conversational fantasies.
He said he was going to open a business next year, but I think he was just whistling Dixie.
"Sure is hot!" / "You ain't whistlin' Dixie!