Some Americans were travelling through Mexico when one of them saw a man on the ground having a siesta. "Excuse me, sir," the American said. "Do you know the time?"

The Mexican looked at the American. The he reached over and held the donkey's balls and appeared to weigh them in his hand.

"Ten after two," he said, at last.

"My word!" said the American. He caught up to his tour group and insisted some of the others return with him. "You've never seen anything like this!" he promised.

The group went back with him. Again he asked for the time. Again the guy reached for the donkey's balls. Again, he seemed to be weighing them as he moved them to and fro. Finally, he announced, "Twenty-one minutes past two."

The others were amazed. They went on their way, but the original discoverer of the miracle time-teller remained. He leaned over, "Listen," he confided, "I'll give you twenty dollars if you  show me how you do that."

The Mexican thought for a moment and then nodded. Pocketing the twenty-dollar bill, he beckoned for the American to kneel down where he was. Then he took the donkey's balls and gently moved them to the side out of the way, and said, "Do you see that clock over there?"