The way I learned it in grammar school (1960's) was:

HORSE CALLED NAPOLEON

I once had a horse, and his name was Napoleon;
all on account of his Bone-y-parts.
He was sired by an old Hambletonian
known to everybody 'round these parts.

Oom-pa-da, oom-pa-da, Oom-pa-da, oom-pa-da

He was so thin you could look right through him,
His hair was as fine as any silk.
He pulled me in my old milk wagon
and I taught him to stop I hollered milk.

Oom-pa-da, oom-pa-da, Oom-pa-da, oom-pa-da

Then one day while I was out a-ridin'
along came a feller in a rig so neat.
Says he to me I'll bet you a five-er
Let's have a race right down the street.

Oom-pa-da, oom-pa-da, Oom-pa-da, oom-pa-da

So off we started helter skelter;
I was a-goin' at a thunderin' pace,
But as sure as you're a sinner, I was comin' out the winner
when the feller hollered, MILK! and I lost the race.

Oom-pa-da-la-doom-pa, Too Bad!