Hillbilly Knee Share definition Flag Body part used to navigate a motor vehicle with while changing radio station or conduction an imaginary orchestra. " I use this har hillbilly knee to drives to the licker store for my's beverages". Hillbilly Knee by Hillbilly Wannabe December 30, 2008 0 0 Get merch Get the Hillbilly Knee mug. Buy Now — $32.95 See more merch