mad as a wet hen

In the old south, after a hen laid her eggs she would want to sit on them until they hatch. Even if you gathered up all her eggs, she would still sit on the empty nest. So in order to “break her” and get her to lay more eggs, the farmer would lift her off the nest and dunk her in water. She’d then go right back to her nest, so this had to be done two or three times, after which she’d be mad as hell and start “fussing and scrambling about” Apparently this “broke her” and she’d start laying eggs again.