Hope you don't mind me coming late into this thread !

In my experience, comedy songs such as "Paddy McGinty's Goat", "Delaney's Donkey" and "O'Rafferty's Pig" tend to use very well known tunes. I seem to recall O'Rafferty's Pig being sung to "The Irish Washerwoman". Other than verse 3, the lyrics posted by 'McGrath of Harlow' on 22-Dec-99 seem to fit well enough with a little careful editing. Verse 3 doesn't really seem to fit to any tune that fits the other verses.