I won't post a link so as not to inflict this upon anyone else, but last night, flying up the deserted A12 at 2am on the motorbike, I had this chorus going round and round, as sung by my niece's nursery school:
Kookaburra Kookaburra sits on the old gum tree
Merry merry king of the bush is he
Laugh Kookaburra, laugh Kookaburra
Gay your life must be