What's the deal with your nickname? How did you get it? If your nickname is self-explanatory, then tell everyone when you first started using the internet, and what was the first thing that made you say "wow, this isn't just a place for freaks after all?" Was it a website? Was it an email from a long-lost friend? Go on, spill it.
Agent of selection is an evolutionary term for whatever force or entity exerts selective pressure by effecting relative fitness, such as a predator killing slower animals, or an antibiotic killing non-resistant bacteria. I started using it for a screen name when I learned the term in college because I thought it sounded incredibly badass.