Three men were trying to guess the professions of their respective
 dates of the previous evening, judging by their bedroom
 performance and conversation.
 
 The first insisted that his date had been a nurse, because she
 said, "Lie back and relax.  This won't hurt a bit."
 
 The second concluded that his must have been a schoolteacher,
 because she had said, "Do it over and over until you get it
 right."
 
 The third figured that his date must have been a stewardess,
 because all she had said was, "Put this over your mouth and nose
 and continue to breathe normally."