My last outfit used three-letter codes for everyone, based on your last name. Then there was this one rather annoying guy who had FOS even though that wasn't even close to his name. When I asked I was told it meant Full Of Sh!t.
The funny thing was that he didn't seem to mind. I guess he was so far up someone's fundament that he was bullet-proof but anyway, I am gone now and he's still there. Lots of these nickname-holders are like that, sort of human cockroaches able to survive even a nuclear disaster that would kill a normal human.