Mine got started in high school. We were trying to get a quake clan going, and we thought NUKE would be great initials for it, and we wanted to figure out what we could turn NUKE into an anagram for.
And we came up with Never Underestimate Killer Eskimos. Once we came up with that, i adopted Killer Eskimo as my quake name. It was later shortened just to eskimo, which I've been for many years.
I also became BatDwarf when I used to play Warcraft. I loved batman, and so I a dwarf name Batdwarf, and elf named Batelf, etc, but BatDwarf was the most common one.
Those are the two nicknames I use online. If my name is taken I add 81, or 1981 to the end, because that's the year I was born.