A couple was celebrating their golden wedding anniversary. Their domestic tranquility had long been the talk of the town, and on this special occasion, a local newspaper reporter paid them a visit. He inquired as to the secret of their long and happy marriage. "Well," explained the husband, "it all goes back to our honeymoon. We visited the Grand Canyon and took a trip down to the bottom of the canyon by pack mule." "We hadn't gone too far when my wife's mule stumbled. My wife quietly said 'That's once.' We proceeded a little farther when the mule stumbled again. Once more my wife quietly spoke: 'That's twice.' We hadn't gone a half-mile when the mule stumbled a third time. My wife promptly removed a revolver from her purse, hopped down off the beast, and shot the mule dead." "I started to protest over her treatment of the mule when she looked at me and quietly said, 'Thats once.'"