Guess the mules were tired of having their hooves worked to the bone.
This farmer had a wife who constantly nagged at him. His only relief was to take the mules, go out in the field and start plowing.
One morning she started nagging really badly. When he just couldn't take it any more, he got the mules and went out and started plowing the field.
At noon, his wife brought lunch out to him. They spread a blanket under a shade tree, where he started eating lunch and once again she began to nag.
One of the mules moved around, turned his back side to his wife and hauled off and kicked her, hitting her right in the head and killing her.
At her funeral, he was standing up front, with the casket, greeting friends and neighbors. The Priest, who was standing in the back, noticed that every time the farmer talked with a woman he would keep nodding his head 'yes'. Conversely, each time he talked with a man, he would shake his head 'no'.
The Priest became really curious as to why this was happening, but couldn't talk to the farmer alone until after the service.
When the opportunity presented itself, the Priest approached the farmer and said, "I noticed today that every time you talked with a woman, up by the casket, you would keep nodding your head 'yes'. What were they saying?" The farmer replied, "The women would say things like what a pretty dress she's wearing and what nice jewelry, or how nice she looked."
The Priest then asked, "What was it that the men were saying that you kept shaking your head 'no'?" The farmer said, "Oh, they were asking if the mule was for sale".