Green’s Dictionary of Slang

thimble-rig n.

[SE thimble + rig n.2 (1). Sante, Low Life (1991), suggests this to be one of ‘the only major gambling games actually invented in the United States’. However, neither DSUE nor the OED’s first cit. (Hone’s Every-day Book, 1825) mentions this and Sante himself places its US appearance around 1860]

1. [mid-19C–1930s] a version of the three-card trick, in which punters are asked to bet on which of three rapidly manipulated thimbles contains a pea; it is very rare that anyone other than the sharper’s accomplice manages to bet correctly.

2. attrib. use of sense 1.

3. [mid-19C] in fig. use of sense 1, corrupt, deceptive .

4. [mid-19C] trickery, deception.

In derivatives

thimble-riggery (adj.)

[mid-19C] deceptive, cheating.