kackflap Share definition Flag The act of shimmying one's hips so as to cause the penis to bounce back and forth off of the left and right hip bones. How funny was it when Esteban dropped his pants at the party and showed everyone his kackflap? kackflap by A. Burrows April 24, 2007 0 0 Get merch Get the kackflap mug. Buy Now — $32.95 See more merch