Joe the mechanic decided to hold a challenge for his three so called clever doctor friends (a gynaechologist, a GP and a psychiatrist) who kept telling him he was stupid.
They had to learn how to take apart a car engine and put it back together again.
They all laboured for hours and finally completed the task.
Joe explained "GP scores 50%" - good but not quite right
"Psychiatrist scores 100% - excellent job!"
"Gynaechologist scores 150% superb!"
The Psychiatrist interjects "hang on, you cant give a score of 150%! thats not fair!"
Joe smiles. "I gave an extra 50% for the fact that he did it all through the exhaust pipe"