I'm 52 but when I was a child my 96 year old uncle would quote me a nursery rhyme that has stuck with me till this day. I know there have been many variations but I have always wondered the origin of it. Perhaps somebody could help

'There was a little man
and he had a little gun
and off to the mountains
he did run

With a big tall hat
and a belly full of fat
and a pancake tied to his
bum, bum, bum...'

Then my uncle would sometimes finish by saying 'Giddyup McConkey!'

I'd appreciate any insight I could get.

Thank you