be whistling Dixie

be whistling Dixie

slang To have an unrealistic, usually overly optimistic, view of something. "Dixie" was an anthem of the Confederacy, the losing side of the US Civil War. Primarily heard in US. You're whistling Dixie if you think we're making the playoffs this year.
See also: Dixie, whistle
References in periodicals archive ?
You'll be whistling Dixie when you sink your teeth into a spice cake topped with meringue, a Southern specialty.