Green’s Dictionary of Slang

(US) to swindle, to defraud.

1875		Chicago Trib. 6 July 8/1: The fugitive is the same person who bunkoed a stranger out of $75 recently [DA].
1888		Chicago Daily Inter Ocean 14 Apr. n.p.: John Brothers [...] was bunkoed out of 2,000 dols. to-day by two sharpers who escaped [F&H].
1889		Salt Lake Herald (UT) 22 Dec. 10/2: To escape buncoing, don’t talk to strangers, especially on the street.
1893		J. Hawthorne Confessions of Convict 141: Jimmy Hope, the famous kid-glove bank-burglar, buncoed!
1894		Mirror of Life 3 Mar. 8: [pic caption] buncoed millionaire gould / A Precious pair of Blackmailers.
1898		Binstead & Wells A Pink ’Un and a Pelican 8: Men would rather be bunkoed and bested by a polished, well-dressed villain [...] than be taken out for a whole evening by one who makes no attempt to disguise his moderate circumstances.
1902		Ade Girl Proposition 158: She had buncoed the Family Bible and brought home a new Name.
1903		A.H. Lewis Boss 89: ‘Bunco the foe!’ was the watchword; ‘take their money and “con” them!’.
1907		F.M. Howarth ‘Mr. E.Z. Mark’ [comic strip] Now, for goodness sake, E.Z., don’t tell me you are about to be bunkoed again.
1908		‘O. Henry’ ‘Modern Rural Sports’ in Gentle Grafter (1915) 37: The little devices I had in my pocket for buncoing the pushed-back brows seemed [...] hopeless.
1910		‘O. Henry’ ‘Babes in the Jungle’ in Strictly Business (1915) 38: Do you know of any immediate system of buncoing the community out of a dollar or two [...].
1913		H.A. Franck Zone Policeman 88 247: That’ll do! Because of your gestures I believe you are trying to bunco this court. You are lying.
1926		J. Black You Can’t Win 144: The way to sell a brass brick is to bunko yourself first into the belief that your brick is solid gold.
1927		D. Hammett ‘The big Knockover’ Story Omnibus (1966) 275: This Angel Grace Cardigan had buncoed half a dozen Philadelphia boys out of plenty.
1930		Jefferis & Nichols Safe Counsel or Practical Eugenics 275: They want a man who will bunko the ignorant patients and get the money.
1931		(con. 1900s) C.W. Willemse Behind The Green Lights 134: Superiors are suspicious people and there were those who figured the department was being buncoed.
1939		Howsley Argot: Dict. of Und. Sl.
1949		Monteleone Criminal Sl. (rev. edn).
1977		D. Powis Signs of Crime 175: ‘Don’t give me that, man — I’ve been buncoed by experts!’ means ‘Don’t try to deceive me!’.