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. 
some users usually don't bother themselves on thinking of their usernames they will used. As for me, it is actually the name of my niece.