A man goes to the doctors and says, "Doctor, I've got this problem, only you've got to promise not to laugh."
The doctor replies, "Of course I won't laugh, that would be thoroughly unprofessional. In over 20 years of being a doctor I've never laughed at a patient."
"OK then," says the man, and he drops his trousers. The doctor is greeted by the sight of the tiniest penis he has ever seen in his life. Unable to control himself, he falls about laughing on the floor. Ten minutes later he is able to struggle up to his feet and wipe the tears from his eyes.
"I'm so sorry," he says to the patient, "I don't know what came over me, I won't let it happen again. Now what seems to be the problem?"
The man looks up at the doctor sadly and says, "It's swollen."