In southern california we sang it like this

Down by the banks of the hanky panky
where the bullfrogs jump from bank to banky
where eeps ops
soda pops
hey mr. willy and he went kerplops

Later in my childhood someone corrected me and said it was actually this:

Down by the banks of the hanky panky
where the bullfrogs jump from bank to banky
where he hops
soda pops
he missed a lilly and he went kerplops.