One day, after a decade of practicing medicine, a gynecologist decided he was bored with his job and wanted a change. He realized that he had spent many years working with his hands, and so he decided he would switch to a career that would also require the use of his hands. Not wanting the stress of being a medical professional, he decided to attend vocational school to learn to be an automotive mechanic.
He worked really hard and studied day and night. But when the results of his final exam came in, he was quite perplexed: he got a 150% on the test. The doctor figured this had to be a mistake so he called his instructor at the vocational school.
Doc: "there must be some mistake. It says I got a 150% on the final exam. Could you explain why my score was so high?"
Instructor: "well, for the first part of the test you disassembled the car's engine perfectly. That counts for 50 points on your test."
"You then reassembled the engine perfectly. That got you another 50 points."
"But the last 50 points are bonus points, because none of us instructors have ever seen anyone do all of that by working exclusively through the exhaust pipe."