Green’s Dictionary of Slang

one who does not take sugar in coffee or drinks, e.g. gin and water.

1824		Pierce Egan’s Life in London 3 Oct. 6/2: ‘I’ll thank you for a cup of coffee not too sweet — for I’m no great friend to the grocer’.
1836		T. Hook Sayings & Doings 221: ‘With sugar?’ continued Harriet. ‘ No, I thank you, said Frank. ‘You are no friend to the grocer, then,’ said the smiling girl.