The words have pretty much been modified over the years, and “Whack for my daddy-o” came out of the orginal, “Whack Fol-de-dol-de-o“.

Here are some comparisons between the original folk and Metallica’s version:

Metallica: “…Cork and Kerry Mountains…
Folk: “…Far Famed Kerry Mountains

Metallica: “…or the devil he may take ya…”
Folk: “…For ye were a bold deciever…”

Metallica: “I took all of his money and it was a pretty penny”
Folk: “I counted out his money and it made a pretty penny”

Metallica: “I took all of his money yeah I took it home to Molly”
Folk: I put it in me pocket and I took it home to Jenny”

Metallica: “She swore that she’d love me, never would she leave me”
Folk: “She sidled and she swore that she never would decieve me”

Metallica: “But the devil take that woman for you know she treat me easy”
Folk: “But the devil take the women for they never can be easy”

Metallica: “Whack for the daddy-o”
Folk: “Whack Fol-de-dol-de-o”

Metallica:
“Being drunk and weary I went to Molly’s chamber
Takin’ my money with me and I never knew the danger
For about six or maybe seven in walked Captain Farrell
I jumped up, fired off my pistols and I shot him with both barrels”
Folk:
“I went into my chamber all for to take a slumber
I dreamt of gold and jewels and for sure it was no wonder
That Jenny drew me charges and she filled ‘em up with water
Then sent for Captain Farrell to be ready for the slaughter”

Metallica:-Nothing-
Folk:
” ‘Twas early in the morning just before I rose to travel
Up comes a band of thug men and likewise Captain Farrell
I first produced me pistol for she’d stolen away me rapier
but I couldn’t shoot the water so a prisoner I was taken”

Metallica:
“Now some men like the fishin’ and some men like the fowlin’
And some men like ta hear, ta hear cannon ball a roarin’
Me I like sleepin’ specially in my Molly’s chamber
But here I am in prison, here I am with a ball and chain yeah”
Folk:
“Now there’s some take delight in the carriages a rollin’
and others take delight in the harley and the bowling
but I take delight in the juice of the barley
and courting pretty fair maids in the morning bright and early”

Metallica: -Nothing-
Folk: “If anyone can aid me, tis me brother in the army
If I can find his station in Cork or in Killarney
and if he’ll go with we’ll go rovin’ in Killkenney
and I’m sure he’ll treat me better than me only sporting Jenny”

The long and the short of the song?

A man steals money from the Army, goes home to his girl friend, getting drunk and tells her how bad he’s been, he passes out, and she takes the money and returns it to the Army, who come after the man and arrests him.