Green’s Dictionary of Slang

shit ass n.

(US) a contemptible person; also attrib.

c.1940		‘The Castration of the Strawberry Roan’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 95: I loses both stirrups, my Stetson, my rein, / And I makes a grab for that shitass’s mane.
1952		joke cited in G. Legman Rationale of the Dirty Joke (1972) I 67: Come on, Shitass, if she don’t believe me, she’ll never believe you.
1967		(con. 1920s) J. Thompson South of Heaven (1994) 116: That shitass! I mean a real lawyer.
1969		‘Iceberg Slim’ Mama Black Widow 180: G’wan shitass, before I put some knots on your head.
1973		E. Bunker No Beast So Fierce 164: Shitass, you were off sucking some broad’s cunt when you should’ve been taking care of business.
1973		D. Williamson What If You Died Tomorrow (1977) II i: That’s why! You shitarse!
1975		E. Torres Carlito’s Way 83: Reggie is a shit-ass and he knows it.
1977		A. Brooke Last Toke 157: ‘Get your shit-ass over here,’ Kojak ordered.
1986		R. Hewitt White Talk Black Talk 179: ’Ere comes the shit breader!
1988		D. Woodrell Muscle for the Wing 181: Oh, that sly shitass.
1999		T. Dorsey Florida Roadkill 84: An untested, ungrateful [...] fast-buck shit-ass like minimum.
2000		C. Cook Robbers (2001) 181: He dumped me for nuthin and it just knocked me flat [...] Well, that shitass.
2000		N. Griffiths Grits 69: Ee’s a sound twat (most-a a time; a fuckin shite-arse twat, iffa trewth be fuckin telt).
2007		C. Goffard Snitch Jacket 72: Benny! You, you shit-ass, Benny!
2021		L. McInerney Rules of Revelation 200: ‘Remember Shitarse from up the country? Luna was the only one who’d take him’.

In derivatives

shit-assery (n.)

contemptible behaviour.

2017

Twitter 30 Apr. 🌐 I’m Lyndon Johnson and I see 100 days of shitassery.