My cat does this as well when a bird is close by.....they think they are going native with the lingo. Unless he is taking a course on the internet while I am out, my bird is just pretending to speak beak talk.
acorn - fruit of the oak tree: a smooth thin-walled nut in a woody cup-shaped base. acorn cup, cupule - cup-shaped structure of hardened bracts at the base of an acorn. oak tree, oak - a deciduous tree of the genus Quercus; has acorns and lobed leaves; great oaks grow from little acorns. fruit - the ripened reproductive body of a seed plant.
With that loose definition, a coconut can also be a nut. However, a coconut is not a true nut. A true nut, such as the acorn, are indehiscent or do not open at maturity to release its seeds. The seeds are released when the fruit wall decays or are digested by an animal.