1 Terry: So to wrap up this escapade: We’ve saved the bees, defeated Cthulhu, and restored Steve from the shrink ray.
2 Bonnie: Simon got killed in a problematic trolley dilemma.
3 Jane Goodall: But using his existential philosophy skills to save the world. He’d have wanted it that way.
3 Bonnie: True.
4 Steve 1: So, all’s well that ends well!
4 Steve 2: I’m off then! Hooroo!

"Hooroo" is a particularly Aussie way to say goodbye. To qualify as a fair dinkum Australian you have to be able to say "hooroo" when leaving a gathering in a completely natural and unironic/unembarrassed fashion^[1].

My Oxford Dictionary of Australian Colloquialisms defines "Hooroo" as:

Equivalent to "Cheerio" as a farewell.

Which is fine if you know what "cheerio" means^[2]. It also says that the variant "hooray" is also used as a farewell, and then supplies the following citations of usage:

1870 J. R. Houlding, Rural and City Life 257: "We won't come anigh yer house agin to-day; never fear, sir. Hooray!" With that parting salute, away scampered Jerry.

1917 F. J. Mills, Dinkum Oil 73: There was a vast deal of... "Goodbye Auntie, toolraloo Bill... hooray Dick," and so forth.

1931 William Hatfield, Sheepmates 238: "Well, hooroo!" And he was gone in the direction where the fire glowed like a dropped cigarette butt.

1942 Leonard Mann, The Go-Getter 221: "So long, Chris." "Hooray, boy."

1959 Anne von Bertouch, February Dark 193: "We'll see you later. Hooray."

1987 Sun-Herald (Sydney) 27 Jun. 50: "Some of them old fillums are blood interesting. Keep at it, mate. Hooroo."

"Hooroo" remains current in Australian usage, and you'll find people using it fairly often in normal conversation.

[1] And preferably taking a couple of sausages and a slice of pavlova wrapped in a serviette, to have later at home.

[2] "Goodbye" basically.