Ferdinand IV (later Ferdinand I)is the monarch in question. Ferdinand was was King variously of Naples, Sicily, and the Two Sicilies from 1759 until his death.
He was nicknamed both "Re Nasone" and "Re Lazzarone". The first one means King Big Nose (Naso+ the augmentative suffix –one). The second requires some explanation: Lazarus is the patron saint of lepers, and, by extension, all miserable outcasts. Neapolitan members of the "great unwashed peasant masses" were thus called "lazzaroni".
In an age of rigid social stratification, it was not a derogatory term—it was a description. Ferdinand was a notorious simpleton and vulgarian, and he enjoyed hanging around with the common folk down at the port. He was popular, and both names were terms of endearment bestowed on him by the Neapolitan masses.
He was, thus, the Great Unwashed Peasant King; it was an expression of solidarity with the people, and he took no offense at that term or the one about his nose.
https://en.wikipedia.org/wiki/Ferdinand_I_of_the_Two_Sicilies
https://en.wikipedia.org/wiki/List_of_nicknames_of_European_royalty_and_nobility:_F
