1805, "to pluck a stringed instrument;" 1808 in sense of "drop down abruptly;" 1888 as "to hit, wound, shoot." Probably of imitative origin in all cases. Related: Plunked; plunking.
[1839+; fr the hard striking of the plank of a table]
A dollar: my five thousand plunks (1891+)
To shoot (1888+)