In our neighborhood, the customary way to refer to the dads is by "Mr. Firstname". So we had Mr. Joe, Mr. Dan, Mr. Steve. And then me, Mr. Ed. I wasn't going to have any of that, whether they know who Mr. Ed is or not.
I have a Ph.D. and so one day quipped to a 12 year old neighbor in response to a Mr. Ed, "that's Dr. Ed to you." Then she called me "Dr. Mr. Ed", and it stuck. It's the first real nickname I've had since like 8th grade, so I've been using it everywhere.