I like to give people nicknames (often multiple), but when it comes to John Roseberry, I don't believe he needs one because, well, because he's Shihan. He's the only Shihan I know or talk about, so I usually just refer to him that way, as do most people who know him through the martial arts. I think people may take it to mean something along the lines of "O Exalted Super Grandmaster to Whom I Bow in Unworthiness", but when I say it, to me it feels basically like I'm saying "Grandpa".
Shihan can be translated to mean "teacher of teachers", as Sensei is considered to mean "teacher". However, I think a better translation of Sensei is "one who has come before", which would make Shihan "one who has come before those who have come before", or as I already said, "Grandpa". He's the patriarch of the dojo family, and he should be respected as such. That's just my take on it.
In addition to nicknames, I also sometimes assign people theme songs, purely for my own enjoyment. Although I haven't nicknamed Shihan, I have given him a theme song...
