Here's my transcription of the sound file Joe linked to:

THAT'S MY PA
(Sheb Wooley)

Now, back in the country where I was born,
It was on a little old hillside farm,
My pa raised six kids and one of them was me.*
In the fall of the year when the fields got white,
We'd start picking cotton about daylight.
On Saturday, Pa'd take it on to town.*
Then along about dark when ever'thing was still,
We could tell it was Pa coming down the hill,
'Cause he'd rear back and he'd sound off something like this:*
"Hoo-oo-oo-hoo-oo-oo-ah-ha-ha-ha!
Hoo-oo-oo-hoo-oo-oo-ah-ha-ha-ha!"

We'd go out to meet him with a lantern light,
'Cause the roads got crooked on Saturday night,
And he'd come on down the hill and he'd stop in the yard.*
He'd sit up there on that wagon seat,
And he'd say, "Boys, I'm hard to beat,
Two hundred pounds of steel and twice as hard.*
'Cause I'm wild and woolly and full of fleas
And I never been curried below the knees."
And he'd rear back and bellow out a chorus or two:*
"Hoo-oo-oo-hoo-oo-oo-ah-ha-ha-ha!
Hoo-oo-oo-hoo-oo-oo-ah-ha-ha-ha!"
That's my pa.

Said, "I'm rough and ready and I'm 'bout half wild,
And I can whip anybody in a half a mile."
'Course, there wasn't anybody else there 'cept me and little Skeet.*
Said, "I'm just as tough as a hickory briar
And I can dive deeper and come up drier."
And he did it, too, right off that wagon seat.*
It shook him up when he hit the ground.
Pa got up and looked around,
And then reared back and let us have it again:*
"Hoo-oo-oo-hoo-oo-oo-ah-ha-ha-ha!
Hoo-oo-oo-hoo-oo-oo-ah-ha-ha-ha!"

[As recorded by Sheb Wooley, 1962.

I have marked with an asterisk the points where the bass background vocal goes, as I hear it, "Yoop-poppa-toopa-toppa, yoop-poppa-toopa-toppa, yoop."

Rear: "1. To rise on the hind legs, as a horse. 2. To rise high in the air; tower." (Pronounced "rare" in dialect, and in this song.)

Maybe a horse expert can explain "curried below the knees", and maybe a botanist can explain "hickory briar."]