There was a guy in the middle of the desert and his car broke down.
He started walking and he came to a monastery, where he asked them if he could borrow a mule.
The monks lent him one, and they explained that you had to say "Thank the Lord!" to make it go and "Amen!" to make it stop.
So the man said, "Thank the Lord, thank the Lord and thank the Lord!" and the mule took off! He was coming to the edge of a cliff and he forgot how to make it stop.
Finally, at the very edge he remembered, "Amen!" The guy was so relieved he shouted, "Thank the Lord!"