Last updated: 7/15/23
As mentioned elsewhere, the names that we use in public are actually not the names we use inside the system. We have a thing about True Names and how the act of keeping them between ourselves is a way of keeping a part of ourselves ours.
(This tradition applies mostly to the people in the system who are more individual of self. We used to have a lot of fragmentary people who refused names and would only begrudgingly accept designations - the vaguer, the better. They haven't been around in a long while, though.)
Our external names are usually just picked from a list of whatever nouns are related to something we like, or consider part of our Aesthetic(tm) or Vibe(tm). (Examples: Phosphor, Marquis, Kestrel.) There are plenty of exceptions, though. Seren, who opted for an actual name; Capella, who picked her name as an inside joke; Bastion, who wouldn't have picked the name for himself, but keeps it because it was given to him by someone else - something that continues to be meaningful to him.
Our internal names, meanwhile, are actually not that exciting. They're "normal" names. Some of them are more uncommon than others, but most of them... Well, you could encounter people at the grocery store with them, and not think twice about it. Sometimes we pick them from name lists, but very often we'll just end up knowing them out of the blue, after getting to know ourselves.
And honestly, I think that's my favorite part - the fact that, with one or two exceptions, they're all Normal Names. Like, you would expect a hidden True Name to be something over the top like Greenglory, Warden of the Inner Hues, but nah, his real name is... George.
I think for us it emphasizes that, at the end of the day, we're all just... ordinary people, regardless of what assholes and stigma try to make us out to be. And that is the part of us that is most precious and most worth keeping close to heart.
 Except for Lark, who uses his True Name both inside and outside of the system - his stance is that his name is so strongly his that no one is capable of taking it from him.)
 We do not actually have a George in-system. No Georges were harmed by the revealing of their true name.