Part 19 of the series "Southern expressions that will 'take the rag off the bush'" is posted at link
For the earlier posts in this series, look to the left side-bar for links.
My dearest and oldest friend, Forrest Underwood, a native Mississippian, now lives in Pahrump, Nevada. He has been reading this series and sends this hill country "put-down/insult for small brained individuals" from his childhood memories from Baldwyn, Lee County, Mississippi: "A childhood friend used to say, 'I could put your brain in an ant's backend, and it would rattle like a peanut in a wash tub.'"
Now that is a small brain indeed!