Predominantly rural in usage, particularly in the South. Unknown etymology; may be related to plinking.
The act of going into the woods (or field or any place away from one's home/trailer) and using firearms for the sole sake of using firearms. Typically when "plunking," one fires live ammunition at tin cans on fences or tied to strings from branches. Sometimes includes shooting smaller mammals and birds, but not usually. Often, street signs become targets of those who are plunking.
Pickup trucks and beer (domestic, of course) are not necessary to define an outing as plunking, but there is a high correlation between the presence of these items and the act of plunking.
Note that the infinitive "to plunk" is never conjugated in any other way. "Plunked," "plunker," or "plunks" are not acceptible terms. "Went plunking," "redneck who likes plunking," or "is plunking" are the proper forms.
There is a tendency among non-native speakers of Redneck to confuse "plunking" and "boinking." This can prove disastrous.