Green’s Dictionary of Slang

1. an unfit individual, lit. or fig.[fig. use of SE crock, a broken-down horse].

1841		Comic Almanack May 267: What could have made me join those gambling jockeys? / (Out-of-door Crockies).
1892		‘’Arry in Venice’ in Punch 24 Sept. 133/1: Whenever you think it’s ‘a moral,’ that crock, ‘Unexpected,’ romps in.
1900		Sydney Sportsman (Surry Hills, NSW) 17 Oct. 2/3: Follies now-a-days are so fine looking that they don't want to harness up with a crock to appear to advantage.
1927		W.R. Morse ‘Stanford Expressions’ in AS II:6 276: crock — good-for-nothing girl.
1930		(con. 1917) ‘W.W. Windstaff’ ‘A Flier’s War’ in Longstreet Canvas Falcons (1970) 285: We tired rummies and crocks were aware of how dreadful a war was.
1962		S. Longstreet Flesh Peddlers (1964) 18: You’re just a hired hand, like all us crocks.

2. a fool, a foolish idea; a lie [abbr. crock of shit n.].

1948		Heggen & Logan Mister Roberts I ii: I thought that [an opinion] over and I’ve decided that’s just a crock, Doug.
1957		(con. 1943) A. Myrer Big War 195: It’s all a crock [...] what good is religion in a deal like that?
1960		(con. 1940s) D. MacCuish Do Not Go Gentle (1962) 322: I’ll have you know that I came from heaven!’ ‘That’s a crock!’.
1977		Eble Campus Sl. Apr. 2: crock – person or action which is ridiculous, peculiar, farcical.
1984		J. McNamara First Directive (1985) 181: That’s the biggest crock I’ve ever heard.
1997–2000		Da Bomb 🌐 8: Crock: A dislikable person.
2007		T. Dorsey Hurricane Punch 17: Tom Cruise says it’s a crock.
2010		L. Redhead Thrill City [ebook] ‘I heard the relationship ended because you [...] were jealous of her talent.’ ‘Who told you that? What a crock’.
2012		Jamaican Gleaner 29 Feb. 🌐 Please, this is a load of crock!