A guy goes to the doctor's for an examination.
Before the examination, he asked the doctor if he had ever laughed at his patients' problems.
The Doctor replied 'Of course I won't laugh, I'm a professional. In over twenty years I've never laughed at a patient.'
'Okay then,' he said, and proceeded to drop his trousers, revealing the tiniest willy the doctor had ever seen.
Unable to control himself, the doctor started giggling, then fell laughing to the floor. Ten minutes later he was able to struggle to his feet and regain his composure. I'm so sorry,' said the doctor. 'I really am. I don't know what came over me. On my honour as a doctor and a gentleman, I promise it won't happen again. Now, what seems to be the problem?'
'It's swollen,' he replied.