A gynecologist was getting sick of his job and decided that he needed a career change. He'd always enjoyed tinkering with engines so thought he'd become a mechanic.
So he went along to mechanics school and the final test was to strip the engine completely and reassemble it - obviously back into perfect working order. So our gynecologist friend did the test and anxiously awaited the result.
The day he received the results he got quite a surprise, he got 150%! He quickly phoned the instructor and queried the mark. The instructor said "no no that's right. First I gave you 50% for stripping down the engine- a very thorough job. Next I gave you 50% for reassembling it - a fantastic job really, and then I gave you a 50% bonus for doing it all through the muffler.