My Age? Hey I'm still very young...

I was sitting in the waiting room for my first appointment with a new dentist. I noticed his diploma, which bore his full name. Suddenly, I remembered a tall, handsome, dark-haired boy with the same name had been in my high school class some 30-odd years ago. Could he be the same guy that I had a secret crush on, way back then? Upon seeing him, however, I quickly discarded any such thought. This balding, grey-haired man with the deeply lined face was way too old to have been my classmate. After he examined my teeth, I asked him if he had attended DAV Sr Secondary, Chandigarh. "Yes. Yes, I did," he gleamed with pride. "When did you graduate?" I asked. He answered, "In 1975. Why do you ask?" "You were in my class!", I exclaimed. He looked at me closely. Then, that ugly, Old, Bald, Wrinkled, Fat A*s, Grey-haired, Decrepit son-of-a-bitch asked: "What did you teach???"