Aussie version of "Holy Moly" or variants. Slightly archaic/rural (read: Westie/Bogan etc), but still sometimes used by kids in front of Authorities. Also spelt "hoolEy doolEy"
Now don't expect something profound this isn't even a real word so I don't know why it's making me laugh. What difference does it make if I say the word Hoobly?
-Matt Rose, 2023