Green’s Dictionary of Slang

the guts, the stomach; also in fig. use, courage, pluck (or lack thereof).

1902		T.A. Dorgan in Zwilling TAD Lex. (1993) 52: (Johnny Wise Had A Dream At A Fight Where Sam Pruitt Was Winning ‘Hands Down’) In his kishkus.
1908		B. Fisher A. Mutt in Blackbeard Compilation (1977) 120: I’ll slam him on the kishkuss.
c.1926		L. da Costa Kosher Kitty’s Kids II.ii: Hit him in the kiskers, Toni.
1929		S. Ornitz Haunch Paunch and Jowl 8: Partisan cries – ‘Give it to him, Hymie [...] Come on, nanniegoat, butt him in the kischkes (guts)’.
1934		H. Roth Call It Sleep (1977) 361: Fight! Fight! Gib’m haws-fly! In de kishkis – nudder one!
1941		B. Schulberg What Makes Sammy Run? (1992) 211: Hit him in the kishkes.
1959		B. Kops Hamlet of Stepney Green Act I: All your life you sweat your kishkers out to give them a good education and everything they want and what happens?
1959		M. Richler Apprenticeship of Duddy Kravitz (1964) 104: Take care for my kishkas.
1975		(con. 1939) J. Rosenthal Evacuees Scene 4: They want they should take you away – a fire on their kishkes!
1978		L. Kramer Faggots 60: They both discovered how terrified were his kishkas of: a) his poppa; b) his momma; c) himself.
1991		S. Schwartz Lives of the Fathers 133: You could bet the man didn’t wake up in the middle of the night holding his kishkas.
2001		Markbreit & Steinberg Last Call: Memoirs of an NFL Referee 114: It eats your kishkas out. You hate It.
2023		R. Milward Man-Eating Typewriter 32: If she had the kishkas [...] the Liberated Lady should’ve fought back.