Green’s Dictionary of Slang

(US) a general dismissive, derog. expression; it has no specific meaning.

1931		e.e. cummings i sing of olaf n.p.: Olaf (upon what once were knees) does almost ceaselessly repeat ‘there is some shit I will not eat/I will not kiss your fucking flag’.
1960		(con. 1940s) D. MacCuish Do Not Go Gentle (1962) 208: Tojo—eats shit!
1961		L. McMurtry Horseman, Pass By (1997) 134: ‘Eat shit,’ he said.
1972		Frank Zappa ‘Magdalena’ 🎵 But the girl turned around / And said, ‘Go eat shit!’.
1974		H. Crews Gypsy’s Curse 20: Millard [...] looked at me the longest, so I told him to eat shit and die.
1982		G.V. Higgins Patriot Game (1985) 199: Eat shit, numb-nuts.
1987		(con. c.1967) J. Ferrandino Firefight 25: ‘Eat shit and die,’ Vernon shouted over the hammer of the sixty.
1987		A. Rollini Big Bands 64: Gene (who rarely swore) flared up and blurted, ‘"Eat some shit, Pops!’.
1989		D. Waters Heathers [film script] The judge told them to slurp shit and die.
1995		C. Hiaasen Stormy Weather 275: ‘Gimme the money.’ ‘Eat shit.’.
2001		S. King Dreamcatcher 293: ‘Bite shit and die,’ Henry said [...] and picked up the package. He held it out to the armed and masked men in front of him, smiling.
2004		J. Ellroy ‘Hollywood Fuck Pad’ in Destination: Morgue! (2004) 248: Hey, Luis, eat shit and die, you old cocksucker.
2008		T. Dorsey Atomic Lobster 107: Eat shit and die!
2019		N. Walker Cherry 127: ‘What should I tell him?’ ‘Tell him to eat shit and die’.