Recently bought a joke book aimed at my alma mater, NC State University. Being land-grant, historically-agricultural school, a lot of them are "Moo U" or farm/rube jokes. The other half are largely "Pollack jokes" rebranded with another butt. But there was one joke presented as a list of things not to do when visiting fine society ("you don't need to take your corn cobs or magazines to the outhouse; here, they come provided with papers for this purpose," etc), and one of the items on the list was "Do not ask company for Stump Juice when drinks are ordered" or something to that effect.

What is stump juice? I've seen articles hinting at it as a rust-cleaner, and others referencing it like it was some sort of moonshine. I suspect it was it just a farcical "rural" cure-all used to paint country folks in a negative light, but if anyone has more concrete annecdotes, your help would be appreciated.