Green’s Dictionary of Slang

(US) esp. in gambling, small-time, petty.

1911		Seattle Star (WA) 16 Aug. 1/6: The lugged him off the to ‘factory,’ and told him that the U.S. mint was a piker joint compared to this.
1918		Breckenridge News (Cloverport, KY) 17 Apr. 3/1: A Piker Patriot is a man who loudly cheers marching soldiers, but keeps a padlock on his pocketbook .
1923		H.C. Witwer Fighting Blood 365: I realize I have got hold of something which don’t want to be ruined by piker methods.
1933		W.R. Burnett Dark Hazard (1934) 16: He used to think that twenty-five dollars was a piker bet.
1936		J.T. Farrell World I Never Made 191: He’d rather [...] not sell piker shoes.
1952		Lait & Mortimer USA Confidential 226: Instead of being the boss of Westmoreland County, he has a piker interest in one gambling joint only.
1965		J. Thompson Texas by the Tail (1994) 52: They were shocked by the piker notion of ‘never carrying more than fifty dollars.’.