this is one of those songs that mutate. The concept is easy, but memorizing all the details isn't...so people change it and tweak it over & over...I know several versions, each quite different, but obviously the same idea

and it is related to the old poem:

"Great fleas have smaller fleas,
Upon their backs to bite 'em,
And these in turn have smaller still,
And so ad infinitum.

Small fleas have larger fleas
Beneath their feet to go on,
And these in turn have larger still,
And larger still, and so on."