w.k.d. Share definition Flag stands for white knuckle driver. someone who drives hard and fast. Jon: did you see holly in her truck? Ben: yeah! she's a w.k.d. all the way! w.k.d. by noloveforblondie March 27, 2007 0 0 Get merch Get the w.k.d. mug. Buy Now — $32.95 See more merch