Where does the saying Whollie Mollie come from....?

Answer 1

if it's "holy moly" it comes from the odyssey. moly was a poisonous plant in the book. hermes tells odyseus to eat it to help him. the moly is called "holy moly" because it can only been eaten when a god or goddess makes it not poisonous (for lack of a better word)
and that, my friend, is the etymology of the phrase "holy moly" according to my english teacher

Answer 2

I think it is "Holy Moley" and it comes from the Captain Marvel comic books (around 1941). It is an expression of surprise.