Can the word "hunna" be uttered by the Prophet, peace and blessings be upon him, and he orders his Companions not to use it as a kunya (agnomen), without there being a necessity for that, especially since he forbade other things that are uglier without mentioning this word?

Islam encourages modesty, and the Prophet, peace and blessings be upon him, was more modest than a virgin. It is permissible to explicitly mention private parts when there is a need or benefit, as in the Prophet's saying: "Whoever boasts with the boastfulness of the pre-Islamic era of ignorance, make him bite his father's 'han' (private part), and do not use euphemisms." Here, "han" is a euphemism for the private part. The meaning of "boasts with the boastfulness of the pre-Islamic era of ignorance" refers to associating oneself with the claims of the pre-Islamic era, such as tribalism, nationalism, or sectarianism, which is a call to abandon Islam. The wisdom behind mentioning "his father's 'han'" is to remind the arrogant one who boasts with the claims of the pre-Islamic era of the organ from which he emerged. Allah Almighty has clarified that the wisdom behind making people into nations and tribes is for mutual acquaintance, and that the noblest among people in the sight of Allah are the most righteous, not those who engage in bigotry and ignorance.