there are several phrases based on the phrasal verb 'to get out (of)'; e.g., as or like (all) get-out, used to indicate a high degree of something

1838 J. C. Neal Charcoal Sketches 12 We look as elegant and as beautiful as get out.

Mark Twain may have been among the first to add 'all'..

1884 ‘M. Twain’ Adventures Huckleberry Finn xxxviii. 325 We got to dig in like all git-out.
[OED]