Hooroo is a distinctively Australian way of saying “goodbye”.
The "truly wondrous fantasmagorically splendiferously magickal word hooroo" (credited to someone's Uncle
Wally) echoes two likely sources.
It's a bit of a joyous exclamation, as in "Hooroo! hooroo!
hooray!" (Darby O'Gill), and it's also
something of an owl's
hoot, as in "the proper hooroo, hooroo" (The Sword in the Stone).
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