Green’s Dictionary of Slang

1. to humble oneself, usu. to attain a desired goal.

1964		Larner & Tefferteller Addict in the Street (1966) 67: I just controlled myself because this man deals; I said to myself, I don’t want to get in bad with him, I can’t afford to. I have to eat shit, in other words, off of him.
1972		C. Bukowski Erections, Ejaculations etc. 53: When a man gets old enough, trapped enough [...] he’ll suck dick, tit, eat shit to stay alive.
1978		R. Price Ladies’ Man (1985) 99: We were comrades, we did it together; we ate shit, but we ate shit together.
1984		C. White Life and Times of Little Richard 124: Jimi just idolizes Richard. He would eat ten yards of shit to join his band.
1989		M. Amis London Fields 392: Keith rang Mrs O. the next day on his carfone and ate shit in his poshest voice.
1999		Guardian Guide 25 Sept.–1 Oct. 25: Could he [...] be telling us all to go eat shit?
2000		Guardian Rev. 9 June 7: They would have to eat shit and people in this industry aren’t used to doing that.

2. to be utterly contemptible.

2001

(con. 1964–8) J. Ellroy Cold Six Thousand 149: Late tails ate shit. Wayne hated them.

3. to suffer and accept humiliation (unlike sense 1 there is no useful aim).

1941–5		in Campbell & Campbell War Paint 166: [aircraft nose art] Tojo, Eat Shit.
1954		E. Hemingway letter 23 Dec. in Baker Sel. Letters (1981) 844: But all that is just the usual ton of shit that we were born to eat.
1962		R.D. Abrahams ‘Playing the Dozens’ in Jnl Amer. Folklore July-Sept. 210: When the combatants are quite young (just entering puberty) [...] their contest is liable to be short, sweet, and uncomplicated, but the pattern is established: [...] ‘Your mother eats s--t.’ ‘Your mother eats s--t and mustard’.
1967		M. Braly On the Yard (2002) 165: Juleson [...] felt his anger stir. He wasn’t there to eat their shit.
1971		E. Bullins ‘Dandy’ in King Black Short Story Anthol. (1972) 71: No more copping out and eating shit.
1981		A. Weller Day of the Dog 86: I don’t like you [...] I’m going to take you down to Central and make you eat shit.
1986		L. Nkosi Mating Birds 75: Bloody liar, I’ll make you eat your kaffer shit!
1995		J. Stahl Permanent Midnight 78: He was paid to eat shit.
1996		Guardian Weekend 12 Oct. 78/1: ‘We are British, we eat shit’.
2009		L. McIlvanney All the Colours 294: ‘We’ll be eating shit for breakfast, lunch and dinner’.
2011		F. Bill ‘’ in Crimes in Southern Indiana [ebook] [H]er smile was misleading; her lips told him to eat shit.
2019		D. Winslow Border [ebook] Lerner’s not quite ready to eat shit [...] Maybe it’s his new status.