sour, n. — Green’s Dictionary of Slang

sour n.

also sour dough, sour paper

[fig. use of SE sour + dough n. (1)/paper n. (2)]

1. counterfeit money, apparently silver but made from pewter.

1883		J. Greenwood Tag, Rag & Co. 20: The individual mentioned on the paper was a ‘smasher,’ or, in other words, a dealer in counterfeit coin, or ‘sours’.
1931		B. Lubbock Bully Hayes 3: [ironic use] Oh, let me see the old sour-dough.
1949		Monteleone Criminal Sl. (rev. edn) 218: sour dough [...] sour note [...] sour paper Bad checks; counterfeit money.

2. (US Und.) a bad cheque.

1924		G. Henderson Keys to Crookdom 133: Bad checks – the police call them ‘sour paper’ – defraud bankers, merchants, saloonkeepers and other individuals out of thousands of dollars annually. The toll of the sour-paper crook is almost inestimable.
1927		‘Jargon of the Und.’ in DN V 464: sour paper, A bad cheque.
1931		Irwin Amer. Tramp and Und. Sl. 177: Sour.–Anything undesirable or worthless. [...] Sour Paper.–Bad cheques.
1949		see sense 1.

plant the sour (v.) [plant v.¹ (9)]

to distribute counterfeit money; thus sour-planter n.

1883		J. Greenwood Tag, Rag & Co. n.p.: I was a branch of the ‘sour planting’ business. [Ibid.] n.p.: A safer plane, and one more amired by the ‘sour-planter’ herself [etc.].
1890–1904		Farmer & Henley Sl. and Its Analogues VI 300/1: To plant the sour = to ‘utter’ snide (q.v.) silver; whence sour-planter.
1895		J. Greenwood Behind A Bus 134: ‘Smashing’ is the vulgar term for this branch of roguery [...] but among the fraternity it is known as ‘planting the sours’.
1902		H. Baumann Londinismen (2nd edn) 168/1: plant the sour falsches Geld ausgeben.