Green’s Dictionary of Slang

(orig. US) a general pfx used to demean whatever noun it is attached to by implying a monetary rather than emotional basis for its existence, e.g. rent-a-crowd, rent-a-mob, a group of demonstrators who, it is inferred, will turn up purely to demonstrate, irrespective of the actual event; thence in general use e.g. rent-a-nigger, a black private security guard, seen as protecting white interests against black individuals; rent-a pig, rent-a-cop, a security guard.

1965		Took & Feldman ‘Round the Horne’ [radio sketch title] Rent-a-Chap.
1967–8		Baker et al. CUSS 184: Rent-a-cops Campus police.
1975		New Statesman 26 Sept. 356: Students are generally the prime targets of anti-elitists because they can be so easily organised into Rentamobs.
1987		(con. 1968) Bunch & Cole Reckoning for Kings (1989) 289: He sent over some rent-a-pigs. Tried to run us off as a nuisance.
1987		R. Campbell Alice in La-La Land (1999) 57: A security agency that provided rent-a-cops for parties.
1989		J. Doyle College Sl. Dict. 🌐 rent-a-cop [RIT] Campus Safety.
1990		S. Morgan Homeboy 181: She had the rentacop half convinced she was looking for a job application.
1991		B. Hamper Rivethead (1992) 69: No more clipboard kaisers playing rent-a-God.
1996		P. Temple Bad Debts (2012) [ebook] We had the usual rent-a-lefty crowd outside Parliament.
1997		Simon & Burns Corner (1998) 312: All of those rent-a-cops gathered around, laughing at his story.
2000		N. Griffiths Grits 310: Who the fucker all these people? Fuckin rent-a-party, is it?
2001		J. Baker Shooting in the Dark (2002) 284: A rent-a-drool expression on his face.
2003		N. Green Angel of Montague Street (2004) 47: You a cop? Ex-cop? Rent-a-cop?
2010		K. Richards Life 380: She’d have thrown a whole bottle [...] down the wall of the rent-a-house we’d just moved into.
2011		W.D. Myers Carmen 79: The building is empty on weekends except for a rent-a-cop who guards the entrance on the first floor.
2016		Twitter 5 July 🌐 You can’t REnegotiate something NEW, you boil-in-a-bag rent-a-clown.
2020		S.A. Crosby Blacktop Wasteland 13: ‘You and them rent-a-cops was working together’.