A cop stops a Harley for travelling faster than the posted speed limit, so he asks the biker his name.'Fred,' he replies.

'Fred what?' the officer asks.

'Just Fred,' the man responds.

The officer is in a good mood and thinks he might just give the biker a
break and, write him out a warning instead of a ticket. The officer then
presses him for the last name.

The man tells him that he used to have a last name but lost it. The
officer thinks that he has a nut case on his hands but plays along with it. 'Tell
me, Fred, how did you lose your last name?'

The biker replies, 'It's a long story, so stay with me.' I was born Fred
Dingaling. I know -- a funny last name. The kids used to tease me all
the time, so I stayed to myself, studied hard and got good grades. When I got
older, I realized that I wanted to be a doctor. I went through college,
medical school, internship, residency, and finally got my degree, so I was
Fred Dingaling, MD. After a while I got bored being a doctor, so I
decided to go back to school.. Dentistry was my dream! Got all the way through
school, got my degree, so then I was Fred Dingaling, MD, DDS. Got bored
doing dentistry, so I started fooling around with my assistant and she
gave me VD, so now I was Fred Dingaling, MD, DDS, with VD. Well, the ADA
found out about the VD, so they took away my DDS. Then I was Fred Dingaling,
MD, with VD. Then the AMA found out about the ADA taking away my DDS because
of the VD, so they took away my MD leaving me as Fred Dingaling with VD.
Then the VD took away my Dingaling, so now I am Just Fred.'