Green’s Dictionary of Slang

(US) corned beef and cabbage.

1940		Waukesha (WI) Freeman 24 Jan. 3?/3: ‘Jiggs’ – corned beef and cabbage.
1954		J. Steinbeck Sweet Thursday (1955) 255: Jiggs and Maggie, corned beef and cabbage.
2021		wikipedia 🌐 Jiggs dinner [...] is a traditional meal commonly prepared and eaten on Sundays in rural Newfoundland.