Green’s Dictionary of Slang

pain-in-the-ass adj.

(US) infuriating.

1963		Kerouac letter 29 June in Charters II (1999) 366: No Lucien come yet, no Allen, just pain-in-the-ass visitores [sic], as usual.
1986		S. King It (1987) 96: He would go in style, and with no pain-in-the-ass client sitting in the back seat.
1993		L. Rodríguez Always Running (1996) 81: ‘That’s the way I talk to my pain-in-booty, so-called sister’.
1997		Simon & Burns Corner (1998) 119: The juvenile system is such a pain-in-the-ass complication for a working police.
2002		D.H. Sterry Chicken (2003) 47: My husband, that painintheassbastard, you know what he said to me?
2006		P. Shannon Davey Darling 173: Jesus, she was in a pain-in-the-arse mood.
2010		Codella and Bennett Alphaville (2011) 208: Having bid a clipped but polite good-bye to my own pain-in-the-ass D/O at the Housing Command [etc.].
2019		C. Hammer Silver [ebook] ‘[Y]our girlfriend and her pain-in-the-arse lawyer’.