Green’s Dictionary of Slang

1. (US) a general term of abuse.

a.1955		‘King Heroin II’ in D. Wepman et al. Life (1976) 171: He gave me my wings, that dirty rat fuck— / He thought he was slick, only charging a buck.
1965		Poston & Stillman ‘Notes on Campus Vocabulary’ in AS XL:3 195: R.F. [short for ratfuck], n. v.
1976		L. Bangs in Psychotic Reactions (1988) 199: Those ratfucks on Chicago can suck my asshole.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 257: Jack gets death. Ratfuck Bobby resigns as AG.
2005		K. Huff A Steady Rain I iii: It’s that spineless ratfuck, Walter Lorenz.
2016		twitter.com 16 June 🌐 None of you are good enough to spin the unspinnable ratfuck that is Trump.

2. in attrib. use of sense 1.

2018		‘Aidan Truhen’ Price You Pay 8: [S]he was a drug mule in some ratfuck town wherever idiots smuggle drugs into this country.
2023		(con. 1962) J. Ellroy Enchanters 122: Ratfuck Bobby [Kennedy] fucked us [...] I got sandbagged.

3. (US) a damn, e.g. who gives a rat fuck.

1997		T. Kelly Payback 72: Crack dealers — let’s be honest here — outside of their mothers, nobody gives a rat fuck.
2005		C.A. Smythe Unfortunates 33: ‘Who gives a rat’s fuck?’ Eddie snapped.