Green’s Dictionary of Slang

(US) a rich person, used as a surname, e.g. Mr Gotrocks; thus wealth (cit. 1966).

1894		Mirror of Life 17 Feb. 3/4: gotrox: ‘You can't work any dynamite fakes here. There isn’t any use for you to try it.’ Dismal Dawson: ‘Dis ain’t no dynamite. Dis is a accordion’.
1908		W.T. Corlett Amer. Tropics 12: Mr. George Fitzsimmons Earl and valet were of course there, and Mrs. Gotrocks.
1939		M.N. Chappell Back to Self Reliance 179: [...] to gain the approbation, the paternal benevolence, of Mr. Gotrocks. This is the philosophy of work as most people know it at the present time.
1939		T. Wolfe Web and the Rock 322: This is Mr. Maecenas Gotrox speaking.
1942		US Congress Hearings [...] on H.R. 7378 🌐 Unless we already said to idle rich Mr and Mrs Gotrocks, ‘You must reduce your consumption of food.’.
1954		in D. McKay Wild Wheels 93: You could be Mr. Got-rocks or Joe Blow [HDAS].
1965		T. Wolfe Kandy-Kolored Tangerine-Flake Streamline Baby (1966) 213: Baby Jane sitting up in her Park Avenue apartment with her gotrocks.
1969		R.M. Stern Brood of Eagles (1976) 135: ‘And who,’ Tom said, ‘holds the other three quarters?’ [...] ‘Mr. Gotrocks.’.
1974		W.D. Barnard Dixiecrats and Democrats 91: Folsom has been successful in portraying the leaders of business and industry as ‘Mr. Gotrocks from Birmingham!’.
1993		G.C. Gross Editors on Editing 62: [...] or a Big Name in the Lit Biz has deserted his longtime publisher for a big fat check from Long Green and Gotrocks.
2004		Merriam-Webster Online 10 June 🌐 It is notoriously difficult to pin down the origin of slanguage. Mrs. Gotrocks (and her partner, Mr. Gotrocks) are no exceptions.