The word 'kangaroo' was never a joke meaning 'I don't know'
In 1770, Captain Cook's crew recorded the word 'kangaroo' from the Guugu Yimithirr language of far north Queensland, where 'gangurru' names a species of grey kangaroo. A popular legend claims the word actually meant 'I don't know', but fieldwork by linguist John Haviland in the 1970s confirmed the original meaning was exactly what everyone assumed, debunking decades of retellings.