(definition) by Vulgar Tongue 1811 Wed May 04 2005 at 15:53:51
vinegar

A name given to the person who with a whip in his hand, and a hat held before his eye, keeps the ring clear, at boxing-matches and cudgel-playing ; also, in cant terms, a cloak.

The 1811 Dictionary of the Vulgar Tongue.

I like it!