poo knife Share definition Flag a poo knife....a tool used to cut a pice of poo too large to fit round the u-bend of the toilet. often a kitchen kinfe..not too sharp! my poo is gigantic...hold on i'l use the poo knife.! :haha the poo is defeted!!!!! poo knife by tayzor111 October 10, 2006 0 0 Get merch Get the poo knife mug. Buy Now — $32.95 See more merch