I've always assumed it was a kind of private joke. It's playful and is something like what I would imagine an Old Time band might have done years ago.

Ketch is not poorly educated and it seems he has a memory like a sponge. I don't think he would mispronounce a word he's probably heard tons of times in old recordings.

I don't know about his memory, but his use of English is sometimes puzzling.

One of my favorite moments in contemporary music--remember, I'm old--was when Simon & Garfunkle made fun of the mix-up in people's understanding of just who was the famous Dylan. They say in the song: "Dylan Thomas ... whoever HE was." (I wish I remembered the full exchange.)

Regardless, my point is that both Simon & Garfunkle knew exacty who Dylan Thomas was but they couldn't pass up a wonderful joke, and a commentary on the generation gap.

whistle, isn't it one's "hackles" that get raised? It's been quite some time since my cockles got raised.

It would be possible to check to see if other, older string bands pronounce it roo-kus. I'll look into that when I get the time. I suppose it's possible that in the 1920s, say, it was pronounced differently.

frog, why do you reach this conclusion? Ketch is playful; surely you acknowledge that? Why rule it out?

Alright, once again ya'll are over-analyzing things. I'll tell ya Frogbot- I've lived here in rural TN all my life, and Lucy can attest to my lovely downhome accent. ALL the old folks 'round here pronounce it ROO-CUSS. As a matter of fact, the first time I played this tune for my dad, he's like "Where are those boys from? Sounds like they've been around here before!" I believe it must be a regional thang...

[...]Perhaps a much earlier shift was taking place 100 years ago in the South, and was fossilized in a word like ruckus. Maybe. However, I would think it has more to do with creating a more inventive and musical sound on the stressed syllable of the word, as others suggested. Schwas are sort of hard to sing in English, because they are radically reduced in speech and have weaker formant frequencies. Sing the line to yourself, and the vowel itself is barely audible. The rhotic (r) goes right into the plosive (k). But it becomes more prominent when raised to [u]. I recorded myself singing each and found the schwa vowel to be reduced by about 25 ms as well, so the [u] is lengthened as well. So it seems to accomplish a number of things. I'm still curious about the fellow from TN who claims people pronounce it that way, and what exactly the origins of it is.[...]

[How's that for overanalyzing?
Part of the response I got from my brother after I sent him the thread to take a look at.
I love how much lively discussion there is to be had, and information there is to be gleaned, from such a small piece of a song.

missy, what is your mother tongue, may I ask?