My character is usually a colorful name that wouldn;t make it past the site filter system. I figure if I'm gonna play evil, people would likely adress me unfavorably.
A lot of this stuff isn't terribly well-documented. Like Longinus. The centurion that stabbed Christ in the side with a spear. Everybody and their pet grinch knows about the destiny spear, but was he really named Longinus? The Vatican at Rome doesn't release those texts. The name does, however, show up with surprising frequency in that context in various writings that did get out and show up in various other sources, like a supposed transliteration of the New Testament from the Ancient Greek circa 400 AD.
So am I sure? No. Am I fairly sure? Yes - maybe 80-85%, and if I get that sure about something, it usually turns out to be right.
Sometimes, I pick other names that are made up of whole cloth, like my username here, which is not exactly made up, bit is a triple-entendre that came from various other sources. Or I'll just grab one out of the air, like Selena, or one from legend, like Shiggorath, or Nebo, or old texts, like Kur, or Marduk. Sometimes I just pick something fun, like Snoogins, or Fluffy. SwackHammer was kind of fun. After all, I don't have to put it on my license or anything. I might call myself BoneHead if that's what I felt like at the time.