I've never heard it before, either. I have heard this song, however:

De Camptown Races
Gwine to Run All Night
-Stephen Foster. 1850


De Camptown ladies sing this song,
Doo-da, Doo-da
De Camptown racetrack's two miles long
Oh, de doo-da day.
Chorus:
G'wine to run all night
G'wine to run all day
I bet my money on a bob-tailed nag
Somebody bet on the gray.

2. Oh, de long tailed filly and de big black horse,
Doo-da, Doo-da
Come to a mud hole and dey all cut across,
Oh, de doo-da day.
Chorus:
3. I went down South with my hat caved in,
Doo-da, Doo-da
I came back North with a pocket full of tin.
Oh, de doo-da day.
Chorus:

So maybe when some of our Suthren US contingent checks in, they will have more info.