Mine was an easy one "BULLITT" after my favorite car movie, and I am a Steve McQueen fan, and in the movie he has a 68 fastback, my first car was a 65 fastback, hence BULLITT65.
I have used the same name on many forums since the 90's before I came to own my 69 camaro. I still have a 65 fastback, and still love that movie....