This guy, lost in the desert for two weeks, finally spots a small
 oasis and crawls up to it before collapsing. The resident
 missionary finds him just in time, and slowly nurses him back to
 health.
 
 Fully recovered the grateful guy wants to get back to civilization
 and asks his benefactor, "Could I borrow your horse, and give it
 back later, or possibly leave it for you in the next town?"
 
 The missionary says, "Surely, you may, but there's one special
 thing about my horse. Instead of 'giddiup' you have to say 'Thank
 God' to make him go...and you have to say 'Amen' to make him stop.
 He won't respond to 'whoa.'"
 
 Not paying much attention, the guy says, "Sure, Ok," mounts the
 horse and starts off with an initial "Thank God."
 
 The horse starts walking slowly when the the guy repeats, "Thank
 God, thank God," and the horse starts trotting.
 
 Encouraged by this, the guy then shouts, "Thank God, thank God,
 thank God!" and the horse just takes off at full tilt.
 
 However, pretty soon the guy sees a cliff coming up ahead, and
 starts doing everything he can to make the horse stop.
 
 "Whoa!!...Stop!!...Hold on!!" he screams - but to no avail.
 
 The horse doesn't stop! Finally, he remembers what the missionary
 said and shouts, "Amen," and the horse slows just in time, just
 inches away from the precipice.
 
 Relieved with still being alive, the guy leans back in the saddle,
 wipes his brow and audibly sighs, "Thank God."