When I started computer science back in 1992 in Århus, we were all given a numerical username and email address, in my case u901027 (@daimi.aau.dk). After a short while, I got the opportunity to pick my own username, and I opted for viralbus, rather than the more obvious widmann or tmw.
This goes back to my high-school days. I had learnt a little Latin, and my surname Widmann is in Danish often pronounced the same as hvid mand “white man”, so I translated this mispronunciation into Latin as vir albus “white man”.
Unix systems at the time often seemed to limit usernames to eight characters, so viralbus was quite ideal.
These days it’s often hard to find a username that hasn’t been taken – there are just too many other people called Thomas Widmann in this world – so I often end up using viralbus, which is practically always available, even if confusing to other people, who tend to either think I’m a white supremacist or creating computer viruses. 🙁