Retailers of sand from the pits at and about Greenwich, in Kent: perhaps they are styled barbers, from their constant shaving the sand-banks.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Greenhorn * Greenwich GooseNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes