Years and years ago, back when the internet was a baby...
I first got online.
At the time I was the only female construction inspector in my region and when I needed an online name, ConstructionLady seemed to fit the bill.
That was too long to type all the time tho so I became constlady.
Have been ever since, though for a time I used a different name on dating sites, since I'm the only constlady I ever found so far.