Green’s Dictionary of Slang

1. (UK Und.) a fool.

1845–55

B.M. Carew Life and Adventures.

2. (US Und.) an inexperienced salesman used by a high-pressure salesman for small deals.

1935

Sun (N.Y.) 19 Feb. 28/2: The ‘dynamiter’ may use a [...] ‘coxy,’ an inexperienced salesman good for small sales.