deer-killer Share definition Flag n. The brush guard that some rednecks like to put on the front grille of their off-road trucks. I bought a new pickup truck and gave it some skid plates, nerf bars, a 12" lift kit, super swampers, and a deer-killer. deer-killer by fizzle April 15, 2004 0 0 Get merch Get the deer-killer mug. Buy Now — $32.95 See more merch