Duck woo is an attempt to cure diseases by keeping waterfowl as pets and using the oil that coats their feathers to cure said diseases. In reality, it is quackery (rim shot).
'Duct tape' was formerly known as 'duck tape' and did not involve any harm to birds — but referred to a type cloth that was stickyfied.
A 'rubber duck license' enables the holder to drive/pilot amphibious vehicles.
Yellow rubber ducks are a popular bath-time toy for infants. Sometimes such ducks are chucked overboard at sea in vast quantities to see how the water currents move.