The following Southern expression was explained by someone who has mostly lived in the South (U.S.). He first, and most frequently encountered it in the state of Alabama:
“It’s really an emphatic expression. Basically you can say something [any noun] is as something [any adjective] as all get out!
For example, ‘That’s as cool as all get out!’ “
The informant has no background knowledge on the source or meaning of the phrase, and recognizes that it is definitely a rare one even in the context of the South.
Despite it’s apparent rareness this phrase showcases some of the most important characteristics of Southern speech. The phrase makes an active effort to avoid cursing, while still suggesting that the enactor was tempted to. That makes the phrase an expression of extreme feeling whether excitement or disapproval. You would be alerted to the severity of whatever prompted the phrase by the employing of Southern speech to express it properly. The phrase is also composed so that it may be reusable, any number of words could be inserted and although the meaning would change, it would remain a distinctly southern phrase.