While working for an organization that delivers lunches to 
elderly shut-ins, Mary used to take her four-year-old daughter, 
Holly, on her afternoon rounds.  Holly was unfailingly intrigued 
by the various appliances of old age, particularly the canes, 
walkers and wheelchairs. 

One day Mary found Holly staring at a pair of false teeth soaking 
in a glass.  As I braced myself for the inevitable barrage of 
questions, she merely turned and whispered, "The tooth fairy 
will never believe this!"