Green’s Dictionary of Slang

drop game n.

1. (UK Und., also drop trick) a confidence trick whereby the victim is persuaded to pay money for a wallet, ring or some valuable, supposedly found on the ground but actually planted by the con man.

[US]A. Greene Glance at N.Y. I i: I think you can come the drop game there, while I go and sell the silver one.
[US]N.Y. Daily Trib. 15 Oct. 2/2: Bob Neil was [arrested] for trying to ‘come the drop game’.
Grand River Thames (MI) 15 June 2/1: An aged and venerated clergyman [...] was successfully operated on last Thursday evening by New York sharpers, with the drop game.
[US]Broadway Belle (N.Y.) 22 Oct. 4/2–3: I now explained to this ‘green un’ the pocket-book drop game and [...] he left the city a wiser man.
[US]Schele De Vere Americanisms 300: Another danger [...] threatens strangers in the large cities. A man walking before him, pretends to find a well-filled pocketbook, and either offers it to him, minus a certain sum for immediate need, for advertising, with the expectation of a liberal reward, or, with more cynicism, downright suggests a division of spoils. In either case his greed is justly punished by finding himself the owner of a roll of counterfeit bills, and out of pocket for the sum of good money [...] drop-game, as the cheat is called.
[US]Wash. Times (DC) 14 Mar. 6/2: Colored flim-flammers netted $700 yesterday by means of the ‘drop’ pocketbook trick.
[US]R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].

2. in gambling, a trick whereby a gambler substitutes a note of higher value than that which was apparently bet, then reveals its worth and demands to be paid the correspondingly greater winnings.

[US]J. O’Connor Wanderings of a Vagabond 377: What, pay you $1,000, you big thief! Why, you’ve already lost that bill twice, and then snatched it up and put $50 in its place. Playing a drop game, are ye?

In compounds

drop gamester (n.)

(US Und.) a confidence trickster who performs the drop game.

[US]N.Y. Daily Trib. 13 Nov. 4/1: A drop gamester named Charles Granger.