Green’s Dictionary of Slang

shit ass n.

also shit-arse, shite-arse, shit breader
[shit n. (1a)/shite n. + arse n. (1)/ass n. (2)]

(US) a contemptible person; also attrib.

[US] ‘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.
[US] 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.
[US](con. 1920s) J. Thompson South of Heaven (1994) 116: That shitass! I mean a real lawyer.
[US]‘Iceberg Slim’ Mama Black Widow 180: G’wan shitass, before I put some knots on your head.
[US]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.
[Aus]D. Williamson What If You Died Tomorrow (1977) II i: That’s why! You shitarse!
[US]E. Torres Carlito’s Way 90: Reggie is a shit-ass and he knows it.
[US]A. Brooke Last Toke 157: ‘Get your shit-ass over here,’ Kojak ordered.
[UK]R. Hewitt White Talk Black Talk 179: ’Ere comes the shit breader!
[US]D. Woodrell Muscle for the Wing 181: Oh, that sly shitass.
[US]T. Dorsey Florida Roadkill 84: An untested, ungrateful [...] fast-buck shit-ass like minimum.
[US]C. Cook Robbers (2001) 181: He dumped me for nuthin and it just knocked me flat [...] Well, that shitass.
[UK]N. Griffiths Grits 69: Ee’s a sound twat (most-a a time; a fuckin shite-arse twat, iffa trewth be fuckin telt).
[US]C. Goffard Snitch Jacket 72: Benny! You, you shit-ass, Benny!

In derivatives

shit-assery (n.)

contemptible behaviour.

Twitter 30 Apr. [Internet] I’m Lyndon Johnson and I see 100 days of shitassery.