Green’s Dictionary of Slang

jim crack n.

[euph.]

(US) an act of defecation.

1845
185019001950
1956
[US] in N.E. Eliason Tarheel Talk (1956) 154: [A train companion was left behind] at the Warrington depot, he having gone to the tavern to take a Jim Crack.
[US]N.E. Eliason Tarheel Talk 187: For excretory functions there are two or three slang terms, such as take a Jim Crack.