The following is one of my all-time favorites, and if you've never seen it, I thought you might find it amusing . . . 
 Blaine Greenfield
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Waiting
        
Have you been guilty of looking at others your own age and 
thinking . . . surely, I cannot look that old? [You better say YES, 
you KNOW you've done it--several times!] 

Well, then, you may enjoy this short story.  
 
While waiting for my first appointment in the reception room of 
a new dentist, I noticed his certificate, which bore his full name.    

Suddenly, I remembered that a tall boy with the same name had been 
in my high school class some 40 years ago. Upon seeing him, however, 
I quickly discarded any such thought.
        
This balding, gray-haired man with the deeply lined face was way too 
old to have been my classmate.  After he had examined my teeth, I 
asked him if he had attended the local high school.   

"Yes," he replied!
 
"When did you graduate?" I asked. 
 
He answered, "In 1967. Why?"
        
"You were in my class!" I exclaimed. 

He looked at me closely and then the son of a bi*ch asked,   
"What did  you teach?"