Any history spudguns need to start at the real beginnning. That's a couple hundred years before "joe-sixpack" got involved.
From the SpudWiki History page
It appears that Alessandro Volta (as in Volt) built the first electrically fired combustion "spud gun" in the 1780's;
The "electric-phlogopneumatic" pistol was thought up by Volta. It was generally filled with a mixture of hydrogen and air, and then corked up. One of the electrodes was touched with one hand; the other hand touched one of the poles of an electrostatic machine. When the spark went off between them and also inside the pistol, a loud explosion resulted which violently shot out the cork. As Volta himself wrote, these experiments "stupefied the ordinary observer, caused considerable satisfaction among amateurs and those in the know, for these are experiments combining electricity and inflammable air". They responded to the double requirement, which was popular at the time, of "being showy" and of popularizing the latest scientific results.
(from , see also  and )
Apparently, even eighteenth century scientists enjoyed launching random things, with accompanying loud noises, for the shear joy of doing it. So spudders, when asked, you can describe your hobby as "Following in the footsteps of great scientists like Alessandro Volta". --Jimmy101
EDIT: I can't find a specific reference but I suspect Volta invented the first fuel meter (for measuring hydrogen gas).