When I started playing WC at the age of 9 to 10, I used generic "cool" callsigns, like "Falcon", "Hawk" ("Thundercougarfalconbird") etc. Since I've read the Chanur series (~ 12/13, I guess(, I started using "Mekt-Hakkikt" in every WC game...and pretty much every PC game.
I have always used 'Bandit' as my in-universe callsign when allowed. My family had a great dog named Bandit when I was a teenager and it was in honor of her (not intentionally ripping off Indiana Jones )
I added LOAF to the name when I wanted something that would feel distinct in the early days of the internet. Hard to believe but back then message boards and newsgroups didn't require any sort of registration so you'd have a thousand 'Mavericks' on a WC forum...
Back in the day before the carpal tunnel set in and I could hold a joystick for more than half an hour, I used to fly under the callsign 'Microchip'. I don't know why; one of those things your thirteen year-old self thinks of one day and it just kinda sticks.
Nowaways, I'd probably fly under my usual gamer handle, which is 'Crapsack'. You know, something a little more akin to a real pilot's callsign...
I use to use "LeHah" because it was easy to spell and remember but eventually settled on "Tasker"... and now wish I could go back in time and decided to use that moniker for the last 20 years on the internet!
I started as Sylvester, which was bestowed on me when I went to aviation challenge as a 12 year old with a lisp. I joined the CIC forums the next year so that's what I picked and I used that pretty consistently until I actually became a US Naval Flight Officer. At that point, I switched to my actual callsign in the Navy, which is Sid (you may be sensing a theme...).
In the way, way beginning, I picked "Snoopy" as first callsign. Seemed appropriate for someone constantly fighting the cat next door (and not always winning).
I later switched to "Toast", since Snoopy, though his combat record against the Red Baron and World War II might be distinguished and yet inenviable, was nevertheless famous and I am not, so I backed off to something more anonymous.