Lots about "musha," not so much about "daddy-o"/"laddie-o."

I accept that it's a nonsense chorus, but I'd still like to learn how to pronounce and sing it "authentically," or at least closely enough not to embarrasss myself.

In my very limited experience of Ireland ~ a one-week visit four Augusts ago ~ I heard a few renditions of this old favorite, and no one performer pronounced these nonsense-chorus syllables exactly the same as any other. A trio I heard in Lisdoonvarna gave perhaps the most remarkable interpretation, featuring consonant sounds completely alien to the English language (which I surmise must have been Gaelic). My reaction was that anything I myself was unable to pronounce was very likely to be authentic, something I might do well to try learning.

This discussion reminds of a similar thread about the Mardi Gras Indians and some of their phrases, like "Jockamo fee nah nay" (or "fee on day," the preferred Ninth Ward pronunciation) and "Honda Wonda Yo Mama," etc., which may once have had literal meanings that no one knows any longer, and which may or may not come from French/African/Creole/Choctaw patois. No one has any firm answers, there is no one "correct" version, but a discerning listener can still tell the difference between a true insider's vocal performance and a poorly-informed imitator's.