Some folk here in the highlands of Mississippi (of which there are none) understand "get out" to be the diminutive of "all get out". As in:
"Get out an extra clean plate; Aunt Gussie's* coming over for supper" or
"Get out the cloth tablecloth, the un-chipped China, the matching silverware, and put on your manners; Reverend Jackson's coming for dinner".

And maybe "all get out" trans-mutilated into "get up" as in overdone attire such as a phony cowboy's outfit, but not "git-ty up" which likey means "get up and go, horse".

*My sweet Aunt Gussie always wore too much make-up. She was always "gussied up".