Gwhap Share definition Flag striking another in the face and or on the forehead or any part of the body with ones male genitals; the sound produced from said slap. "i will gwhap you", "come here let me gwhap you." Gwhap by kel.VS.IS October 28, 2011 0 0 Get merch Get the Gwhap mug. Buy Now — $32.95 See more merch