Green’s Dictionary of Slang

1. a brothel.

1931		Irwin Amer. Tramp and Und. Sl. 45: Cab Joint. – A brothel or ‘heifers’ den’ to which patrons are driven by taxicab, the drivers usually, or in many instances, receiving a certain fee or percentage of what the patron spends in the ‘joint.’ This arrangement was much more common in the days of horse-drawn cabs, and before the reformers had managed to upset such procedure on the part of the disorderly resorts, but the term has survived.
1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 39/1: Cab-joint. A restaurant that charges exorbitantly; a brothel or other illegal establishment whose patronage depends upon taxicab-driver steerers.
1972		R.A. Wilson Playboy’s Book of Forbidden Words.
1986–7		Maledicta IX 149: The original argot of prostitution includes some words and phrases which have gained wider currency and some which have not […] cab joint (sex establishment existing on taxidrivers’ recommendation when asked ‘Where is there some action in this town?’).

2. a nightclub to which patrons would be steered, were they to request such a place, by a complaisant cab-driver.

1950		see sense 1.
1962		Ragen & Finston World’s Toughest Prison 793: cab joint – A brothel to which patrons are driven by taxicab, the drivers usually, or in many instances, receiving, a certain fee or per centage of whatever the patron spends in the ‘joint.’.