There was this bloke who had a dog which he was attempting to
 train, but alas had very little success.  He was on the verge of
 despair when he happened across a very charismatic American
 evangelist.  He unburdened his soul to the American, who promptly
 informed him to leave the dog with him, and he would have it
 trained in a jiffy.

 The next day the man returns, and asks how the evangelist got on.
 The reply was positive, and the evangelist calls the dog to give a
 demonstration.

 Picking up a stick, he throws it and says `Fetch.'  Instantly the dog
 takes off, grabs the stick and returns.  The evangelist says `Drop'
 and the dog drops the stick at his feet.  `Roll over' and the dog
 rolls over.  By this time the dog's owner is very excited, and asks
 if
 he can have a go.

 "Sure," replies the evangelist.

 "Heel," says the owner

 and the dog lifted one paw, placed it on the man and said "I
command this sickness to leave you..."