"Jimmy-John" is probably folk etymology for "demi-john". See this excerpt from http://en.wikipedia.org/wiki/Carboy

"A carboy is a container for fluids, typically used for in-home fermentation of beverages, often wine...

In brewing, a carboy is also known as a demijohn. It is a glass or plastic vessel used in fermenting beverages such as wine, mead, and beer. Usually it is fitted with a rubber stopper and a fermentation lock to prevent bacteria and Oxygen from entering during the fermentation process."

-snip-

Also, see this repost from another Mudcat thread:

Subject: RE: Req/ADD: Poor Howard (from Leadbelly)
From: MikeofNorthumbria - PM
Date: 14 Mar 09 - 09:50 AM

Justr a thought about "stand around the demi-john"

I remember reading somewhere (sorry, no reference available) that old-time dancers sometimes demonstrated their skill by stepping around - and over - a demi-john (a gallon liquor jar) without touching it (A bit like the bacca-pipes jig or the broom dance.)

Since "Green corn" is clearly a dance tune, this might be how the demi-john got in there.

Wassail!

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