Way back when I first got into The Sims and posting legacy challenges, it was TS2, on LiveJournal. I wanted a punny username with 'Sim' in it somehow, and was trying to brainstorm with my best friend. She joked that I've unusual taste in music, my sense of style etc so 'Simsual' was born -- 'unusual' with 'Sim' in it.
...come to think of it, my username doesn't sound that clever at all, lmao. I did carry it with me when everyone jumped ship for Simblrs (Sims-related Tumblr accounts). Now it just makes sense to have the same username for my Sims-related content.