It's quite interesting on how and where did you get those usernames. And sometimes other guys out there has some catchy and quite funny PM signatures. Last time I was browsing out here in this forum I saw a legendary member here that has a very unique avatar lickin his own tits and i couldn't get over it. 
I'm a huge fan of Game of Thrones. I really love Jon Snow and kinda thought of a good username about him. Then I remembered that episode of Game of Thrones where he lived again and gave me chills. That's the time, for me, he became a king. Long story short, I named my username after him.