1) A crude, but highly alcoholic beverage. Similar to Moonshine, but much more potent, with an alcohol content similar to Everclear (180 proof), but less refined. It is called boomshine because it has a tendency to explode, do to the high amount of alcohol vapor produced
2) A more potent version of moonshine, known to get people drunk off the vapors alone.
Jim Bob took one wiff of Bubba's boomshine and fell flat on his face.