Board Thread:Episode Discussions/@comment-1181222-20180726120028/@comment-24572728-20180801204512

To add the the previous post/reply, it's a Japanese colloquialism. Boruto if I remember correctly calls Naruto "oyaji" which comes from a word which translates to "father". It's just that it can be rude to use the term to someone who is not your father or if you don't mean father. Just like oji-san is uncle (ojii-san is grandpa not to be confused), but oji-san can also be a rude term when used for an older person who is not your uncle.