The Proctological Mechanic

A gastroenterologist had been in practice for 20 years and had settled into a very comfortable life with his future being very secure.  So he decided to fulfill his REAL life's dream and become an auto-mechanic.

Having entered mechanic school, the former physician received the results of his first test back with a score of 200%.  Confused, he asked the teacher why such a high score... 

"Well", said the teacher, "The first part was taking the engine apart and you did that perfectly so you got 50%.  The second was to put it back together again and you did it perfectly and got another 50%.  The other 100% was for doing it through the tailpipe."