Green’s Dictionary of Slang

so what! see if I care! a response indicating little or no sympathy with the first speaker; also attrib.

1959		M. Richler Apprenticeship of Duddy Kravitz (1964) 95: You make fun of your father. You don’t like him. Tough shit.
1960		(con. WWII) G. Sire Deathmakers 115: ‘Drive carefully — you might hit a kraut.’ ‘Tough shit.’.
1961		R. Gover One Hundred Dollar Misunderstanding 95: Weekend is one hunner, an if the trick don’ stay all weekend, tough shitski, it still cost him one hunner.
1977		L. Heinemann Close Quarters (1987) 158: And the big guy says, ‘Tough shit, kid.’.
1984		(con. WW2) T. Jones Heart of Oak [ebook] ‘Christ, I can’t stand heights’ [...] ‘Hard shit’.
1986		L. Heinemann Paco’s Story (1987) 188: For Christ’s sake [...] fuck you and the horse you rode in on. Tough shit, bub.
1993		Tharunka (Ke sington, NSW) 13 Sept. 36: If you don't like my policies, tough shit.
1997		(con. 1950s) D. Farson Never a Normal Man 212: ‘Tough shit,’ he said. [Ibid.] 312: Deakin was in his ‘Tough shit, kiddo’ mood.
2006		C. Hiaasen Nature Girl 135: Tough shit. I was here first.
2010		L. Redhead Thrill City [ebook] ‘I’ll be recommending you for an award.’ ‘I’d rather you didn’t.’ [...] ‘Tough shit’.
2021		J. Ellroy Widespread Panic 275: Jimmy Dean went tits up in a car wreck. Tuff shit [...] I felt next to nothing.