Here's some related variants from grown-ups printed in the Ozark folklore collection 'Blow the Candle Out' (Vance Randloph / Gershon Legman, 1992, p.689):
Bullfrog jumped from bank to bank,
Skinned his pecker shank to shank.
(Collected 1947, Missouri)
They also cite another version from 'What Happened to Mother Goose' (Ray Wood, 1946):
Down on the river Yank-te-hank,
The bullfrog jumped from bank to bank,
He spread his legs from shank to shank,
And split his hide from flank to flank.