I think I posted it somewhere, but I'll post it again. I'll start in the VERY beginning...
I played a cool Duke Nukem 3d level pack called FTWOAP (From The Wing Of A Plane) a long time ago. In it, you started FTWOAP and then killed monsters and so on.
So, in trying to think of a Duke Nukem 3d map I was going to make, I called it FIAT (From Inside A Tree). So Duke Nukem started from in side a tree, and fought monsters and so on. Before I could finish it, the editor (Build) decided that corrupting the map file was a great and woundrous idea, and it was screwed from that day onward. I never did end up releasing any of my DN3d maps to anyone.
Flash forward to late 1999. While reading another accursed poem in English 5, I noticed 'fiat' as a footnote on the bottom of the page. I thought it was cool that a map name I made up was an actual world. The definition was 'control' or something like that. Because I was already deeply entrenched in Dink Smallwood stuff at that time, I decided to make a D-Mod called FIAT, with it having an elemental theme where a boss character had the power of 'control'.
So... in the D-Mod FIAT, Dink actually starts From Inside A Tree (then the wizard burns him out), and the boss FIAT 'controls' the other monsters, raises the dead and so on.
I learned of the FIAT car long after I made up the acronym.