Source: npl-folk email from Munro.
First Issue: Jun 1984
When I joined, I offered a prize (a copy of TCC, which Quip & I wrote) to the first member to figure out the derivation of my nom. Nightowl won, even though circumstances gave a few other top solvers a considerable head start.
My nom comes from H. H. Munro's pen name, SAKI, which I, Stanley A. Kurzban, could use to introduce myself thus: “S. A. K., I!”