crackerbarrel, adj. — Green’s Dictionary of Slang

crackerbarrel adj.

[crackers adj. + SAmE crackerbarrel, of a philosophy, plain or unsophisticated]

crazy, eccentric.

1961		Hartford Courant (CT) 25 Aug. 8/4: The first meeting [...] will be a ‘cracker barrel session’.
1974		P. Adam-Smith Barcoo Salute 158: For the rest of the tour, apart from going out of our way on what the Americans call ‘cracker-barrel’ lines, we each had a luxurious compartment.
1982		P. Redmond Tucker and Co 83: She’s crackerbarrel really, he told himself.
1991		Cooper & Wright New Jack City [film script] Cracker barrel, cracker ass.