I remember it sounding something like this, at least towards the end:

I've ate, I've ate, and what have I ate?
I've ate the toe of the mallard
Toe and toe, foot and foot, leg and leg, nameless purple slithery viscera and nameless purple slithery viscera*, [continues for some time], neck and neck,
It all went into the pillagey-o**!
Most pitiful*** neck of the mallard.

*Or words to that effect
**This is definitely what the guy on the record was singing.
***This, on the other hand, was probably 'beautiful'.

(I suspect IB knows all this, if not more...)