A cop stops a car for traveling faster than the posted speed limit.
Since he's in a good mood that day, he decides he might give the
fellow a break and write him out a warning instead of a ticket. So, he
asks the man his name.
"Fred," he replies.
"Fred what?" the officer asks.
"Just Fred," the man responds.
When the officer presses him for a last name, the man tells him he
used to have a last name but lost it. The officer thinks he has a
nut case on his hands but plays along with it. "Tell me Fred, how did
you lose your last name?"
The man replies, "It's a long story so stay with me. I was born
Fred Dingaling. I know, funny last name. The kids used to tease me all the time.
So I kept to myself. I studied hard and got good grades.
When I got older, I realized that I wanted to be a doctor. I went
through medical school, internship, my residency, and finally got
my degree so I was Fred Dingaling, M.D.
"After a while, I got bored being a doctor so I decided to go back to
school. Dentistry was my dream. I got all the way through school
and got my degree, so I was now Fred Dingaling, M.D, D.D.S.
"I got bored doing dentistry, so I started fooling around with my assistant.
She gave me VD. So, I was Fred Dingaling, M.D., D.D.S.,
with VD. Well, the ADA found out about the VD, so they took away my D.D.S.,
so I was Fred Dingaling, M.D., with VD. Then the AMA found out about the ADA taking away my D.D.S.
because of the VD, so they took away my M.D., leaving me as Fred Dingaling with VD."
"Then the VD took away my dingaling, so now I'm just Fred."

The officer walked away in tears, laughing.