Green’s Dictionary of Slang

for cat’s sake! excl.

(US) a euph. for for Christ’s sake! excl.

1921		Dos Passos Three Soldiers 61: ‘For cat’s sake quit that coughin’. Let a feller sleep,’ came a voice from the other side of the tent.
1930		R.E. Howard ‘Sailors’ Grudge’ Fight Stories Mar. 🌐 You lay off him till this picture is finished! For cat’s sake!