Before slaughtering poultry, some people will fill the poultry with some water. This process is called "irrigation", and its purpose is to make the blood in poultry easier to flow out, thus reducing the amount of bleeding after poultry death.
The specific method of irrigation is to lift the head of the poultry up, and then use some tools to inject water from the mouth into the throat of the poultry. This process requires care to avoid choking or suffocation of poultry.
It should be noted that irrigation is only applicable to the killing of poultry, not other animals or humans. In addition, irrigation is not the method used in all areas, and some areas may use other methods to reduce the amount of bleeding.