German Knuckle Cake Share definition Flag Fisting with a vengance. Giving the anal blitzkrieg. Chris loves to get a German Knuckle Cake for his birthday! German Knuckle Cake by Big_Daddy_Shame_Train April 19, 2006 0 0 Get merch Get the German Knuckle Cake mug. Buy Now — $32.95 See more merch