In my trade there are many nicknames. I worked for a great guy called Ollie. When I saw the name Earl Stanic, I didn't know it was the same guy. I am known as Big Jim. I know guys like, The Cobb, Davey, Jonesy, Klag, DS, My Tye, Cowboy, Montana, Hoochie Momma, etc. We are very informal. I am a supervisor and hate to be called Sir. First of all I am not better than the people that work with me, I just serve in a different role. Plus, some of it is from the Marines, I was an NCO, not an officer and most NCOs didn't want tto or like being called a "Sir". Right after boot camp, while awaiting assignment to a ITR platoon, I spend a few days working in a supply depot. I called a Gunny "Sir". LOL whoa did he let me know my mistake. Never did that again.
My family all calls me Jimmy because as a child it separated me from Uncle and Grampa Jim. I am Jim, not James. I always addressed my family seniors by Aunt, Uncle Grandpa followed by their name. I introduce myself as Jim. I am Jim, I am proud of the Jim I am, that is all I want to be to people. My grand kids call me Gtrandpa Jimmy, my nephews uncle Jimmy, Its enough for me.
In my family if something is modified in some manner it is "Jimmyed" LOL Jimmy the modifier.