Duck as in the common name for a type of bird belonging to the family Anatidae of the Order Anseriformes... You mean that? Do you say "duck" as in the meat of this aforementioned animal? Are you referencing a type of heavy, plain-weave cloth? Or are you telling me to duck? If so, what's the imminent threat to my head? Unless you mean "duck" as in "submerge your head in the water (briefly)"... Explain.