Green’s Dictionary of Slang

(US teen) exhausted, tired out.

1943

‘Some American Idioms from the Yiddish’ in AS XVIII:1 Feb. 45: A curious employment of the word cack is to be heard among the Jewish boys who comprise the greater part of the student body at the National Farm School, Doylestown, Pennsylvania. They speak of being ‘cacked out’ when they mean ‘physically exhausted, tired, played out.’ [...] a person without strength or energy ‘has no cack.’.