I'd started writing a story with robots when I was a kid, and the main robot was an “RX” model (for Robotic eXperiment). And as my username at the time was already taken, I tried this one and it finally became my main one.
Something my college teacher started calling me after I grew out a lumberjack beard. They knew me since I was in high school and I had to be clean shaven. Kinda stuck afterwards.
My nickname is an animal that I like very much (in the 1930s it was settled in the forests in the south of my country - in Polesie). It's a raccoon. 1964 is the year of my birth.