Where did the "Aunt B. " come from?

Well of course my name is Brenda, so there is the B.  But it was the loving gesture of my 2 (now grown) nieces part.  An attempt to make fun or a joke about me years ago and it just stuck.  All I can ever picture is Aunt Bea of the Andy Griffith Show tho.  I am not that old!!!  lol.  Thanks Montana and Leah.