be not whistling Dixie

be not whistling Dixie

slang To have a realistic or honest view of something; to be speaking truthfully. "Dixie" was an anthem of the Confederacy, the losing side of the US Civil War. Primarily heard in US. It sounds like they really are laying people off in January. You weren't just whistling Dixie, Bob! They've threatened to fire their missiles on civilians; I don't think they're whistling Dixie.
See also: Dixie, not, whistle

not be whistling Dixie

AMERICAN
If someone is not whistling Dixie, they are being honest or realistic and should not be ignored. `Is that a threat?' — `I'm not just whistling Dixie.' He was not whistling Dixie last month when he told financial analysts that the firm is as competitive as ever. Note: Dixie was the name given to the region of the southern and eastern United States which formed the Confederate side in the Civil War. The area gave its name to several songs which were popular as Confederate war songs.
See also: Dixie, not, whistle