I have two nicknames: Brina and Dezi. The only person that can use Brina is my mother. I was given Dezi by a one night stand after he found out my middle name. I'm not kidding. I'm not really good at nicknames but I sometimes introduce myself at Dezi or write it as my name.
One of my students has taken to add a 'Y' to my last name and calling me that. It makes me laugh because it's my father's old nickname from the military.
So what's in a name? However you react to it, I suppose.