Green’s Dictionary of Slang

rig n.1

[? SE rig, to play the wanton, to romp about; ult. ety. unknown]

1. [late 16C–mid-19C] a wanton, promiscuous woman.

2. [mid-19C] a smart, ‘sharp’ young man.

In derivatives

riggish (adj.)

[late 16C–19C] lecherous, amorous, lascivious.

In phrases

go the rig (v.)

[mid–19C] (UK Und.) to enjoy oneself.