“eigenwijsje” was the only other name my father ever called me, besides my real name. “eigenwijs” is Dutch for stubborn or opinionated. The “je” is used in colloquial language to signal a diminutive.
My father disliked all the nicknames that people gave me or anyone for that matter, and never used a nickname for anybody.
“eigenwijsje” is what he used to call me from time to time. Especially when I was trying to explain him why I was doing something in a specific way.