A more thorough explanation:

A cucking stool is a device used in the past to punish scolds by repeatedly plunging them underwater. It was also used to punish bakers and brewers by ducking them into "stinking water". The device is mentioned by the ancient Saxons and in Domesday Book. It is also known as a ducking stool, castigatory, or trebucket.

For example, if a woman was convicted of being a common scold, she would be sentenced to be placed in the cucking stool. The stool would be plunged into the water, and the woman would be repeatedly dunked as punishment.

This punishment was used to shame and humiliate the person being punished. It was believed that the repeated dunking would help to "cool their tongue" and stop them from being a scold.