my student ID at university. I use it 'cos it incorporates my name and has not yet been taken anywhere I’ve shown up.
I like pie. I really do.
I like esoteric cars that few besides devout motorheads have ever heard of. Lancias, of course, top the list.
So wait a second here, you are not Mark Twain? Get out 
Capt
Many years ago I went on a camping trip with a group of new friends . When I was introduced around, one of the girls said, “Isn’t he the blondest bear ever?” Thus I became blondebear.
If your middle name is Langhorn, well, reports of your demise have been greatly exaggerated.
My son’s wildly incorrect pronunciation of his own name when he was learning to talk. Short, unique, and looks foreign or mysterious (cue someone from outside the US telling me it means something rude in their native tongue 
).
Combination of my last name and this.
My original user name was FirstName+LastInitial, which after while I found boring and dull. So I changed it to my main WoW character’s name, which had taken a bit of thought and time to come up with and I think suits me better.
Because this is my favorite bass guitar to play.
Ephemera is something of no lasting significance, such as a message board post.
Boulter’s Canaries - A short SF story by Keith Roberts, published 1965.
The ‘canaries’ of the title are invisible energy beings who share the Earth with humans.
In a fit of blazing creativity, I just used my RL first name. 
Mine just comes from pure obnoxiousness
I just signed up today, and I tried a few usernames, all of which were taken. So, I thought “UsernameTaken” would be somewhat amusing, especially if some other frustrated would-be user tries it out of spite to find it taken
From a previous thread…
Or, they could have just re-named you John Henryzoid 
And what does it mean when people have -goid tacked to the end of their name? 
No way I’m using ever going to use any part of my IRL name to create a screen name.
And no way I’m going to tell where my screen name comes from. It’s left as an exercise for the reader. It’s intended to be something that at least certain readers will be able to figure out reasonably easily (it’s fairly obvious, I think). And once certain readers figure that out, perhaps a certain few of those will be able to figure out the deeper meaning.
An even more fun thread (although I’m not going to start it myself) would be one where we try to guess the meaning of other users screen names.
I’m amused by the name rowrrbazzle (and yes, I know where it comes from).
Because I was around 19 years old when I first joined anything that needed a username, and was originally Poison Ivy since I thought it sounded oh-so-sexy and mysterious. :rolleyes:
I just keep it now since I have had it so long, even though I don’t find it sexy or mysterious.
initials+last 2 digits of YOB.