Green’s Dictionary of Slang

1. crazy; occas. antithesis, on one’s rocker.

1897		Clipper (Hobart, Tas.) 1 May 6/2: She are goin off her rocker / With the howlin and the rant.
1899		C. Rook Hooligan Nights 79: Wouldn’t a’e worried me off me rocker if they ’ad [seen me].
1902		Eve. Teleg. (Dundee) 25 Nov. 3/3: Innumerable and curious euphemisms for ‘mad’ [...] ‘balmy in the crumpet’, [...] ‘a tile loose,’ ‘soft in the cocoa-nut,’ ‘off his rocker,’ ‘off his nut,’ ‘off his chump’ [and] ‘a little bit off the top’.
1914		R. Tressell Ragged Trousered Philanthropists (1955) 595: The wouldn’t mind betting that ole Misery would finish up by going off his bloody rocker.
1915		F. Garrett diary 22 Oct. 🌐 Blue went away with a red label marked ‘concussion from bomb’ [..] and had gone quite off his rocker.
1917		Boy’s Own Paper XL:2 76: I do not wish to see the book which has–has–has–sent Blundell ‘off his rocker’.
1923		Wodehouse Inimitable Jeeves 66: So the Duke is off his rocker, what?
1930		‘Leslie Charteris’ Enter the Saint 192: One of the men’s gone rather off his rocker and he was trying to chuck himself overboard.
1944		L. Glassop We Were the Rats 58: I think Margaret’s off her rocker.
1953		S. Bellow Augie March (1996) 143: It drove me a little crazy. I wasn’t right on my rocker anyway.
1953		L. Uris Battle Cry (1964) 101: She’d have to be off her rocker to hurt a guy like you.
1955		J.P. Donleavy Ginger Man (1958) 256: I almost went right off my rock.
1962		F. Norman Guntz 31: He just gave me this blank look as though I had gone right off my rocker.
1964		F. Sargeson ‘A Man of Good Will’ in Coll. Stories (1965) 140: Telling him he was clean off his rocker.
1976		in Woodward & Bernstein The Final Days 104: The next day Goldwater called Harlow. ‘Is the President off his rocker?’.
1985		B. Humphries Traveller’s Tool 44: Gwen sounded a bit off her rocker too.
1990		in D. Campbell That Was Business, This Is Personal 21: I think he was beginning to go off his rocker with the life-style and the drink.
1994		G. Disher Crosskill [ebook] ‘You’re off your rocker’.
2000		Eminem ‘The Kids’ 🎵 Stacey knew it was Bob and said knock it off / But Bob wouldn’t knock it off cause he’s crazy and off his rocker.
2012		D. O’Donnell Locked Ward (2013) 223: A young woman was admitted [...] offer her rocker with a drug-induced psychosis.
2013		E. Beetner ‘Going in Style’ in ThugLit Feb. [ebook] ‘I knew this day would come. You've gone off your rocker’.
2022		J. Hannaham Didn’t Nobody Give a Shit 191: This crumbum completamente off his rocker.

2. (Aus.) drunk.

1901

Sydney Sportsman (Surry Hills, NSW) 3 July 1/6: For the missus she was shikkered — / Boozey — off her rocker — tight!

3. in fig. use, acting excessively (though not necessarily madly).

1955		‘Blackie’ Audett Rap Sheet 237: By that time I was practically off my rocker.
1962		F. Norman Guntz 117: He is going to wind up going right off his rocker.
2004		T. Winton ‘Commission’ in Turning (2005) 224: Some of them [...] just drinking or going off their rockers.

4. (UK drugs) completely overcome by a given drug.

2009

R. Milward Ten Storey Love Song 155: She can tell Bobby’s off his rocker.