I found a request for this song buried in a very old thread, but the thread was so confused, and covered so many songs that I thought it would be best to start a new thread for it.

Copied from The MOTley Morris web site (which also has the tune):

The tune [THE IDIOT] was written and sung by Stan Rogers. MOTley Morris uses this tune, with Jon Berger's words to John Barleycorn for the dance The Drunken Idiot.

The John Barleycorn words, written by Jon Berger, are:
^^
JOHN BARLEYCORN

1. John Barleycorn to the sea has gone
In a ship both stout and new,
The thirst to slake of Captain Drake
And all his loyal crew.
To venture brave o'er wind and wave,
The Spaniard for to halt,
And though he die of Spanish grape
He'll live as English malt.

CHORUS: So we'll cut him down and we'll bind him round
And we'll serve him worse than that,
For we'll grind his bones between two stones
And we'll bung him in a vat.
Then we'll drink his health in nut-brown ale,
And we'll raise our glasses high,
For before that he can live again
John Barleycorn must die!

2. John Barleycorn's to the courting gone
All dressed in fine array,
In pewter clad from toe to head
To win a lady gay.
The poetry that he declaims
Will stand him in good stead,
For the ladies fair do all declare
They love it more than bread. [Chorus]

3. John Barleycorn's to the hangman gone
And the reason I'll unfold:
'Tis for robbing honest Englishmen
Of their silver and their gold.
In a grave unknown by cross nor stone
John Barley will be lain,
'Til the rainy days have gone their ways
And he rises up again. [Chorus]