A man goes to the doctor with a headache

A young man goes to see his doctor about his headache -
"Doctor, I have had this terrible headache for months - it is driving me crazy as I just cannot get any relief!"
Doctor: "Where exactly is the pain?"
Man: "Across my forehead, and then down the left side of my face"
Doctor: "And you have tried different remedies for it already?"
Man: "I have tried everything they sell in the local chemist, and nothing gets close to relieving the pain.
I went to a Chinese herbalist, and tried everything he had there, and nothing worked either.
I have tried acupuncture, and that didn't help.
I am at my wits end, doctor, please help me!"
Doctor: "I think we will send you to a specialist for some tests, to rule out some ailments, but in the meantime I will also prescribe you some stronger painkillers. Come back and see me in two weeks."

Two weeks later -
Man: "Doctor, if anything the pain is worse! All across my forehead, and down the left side of my face!"
Doctor: "Did you see the specialist?"
Man: "Yes! He prodded and poked me all over, took blood tests, gave me an MRI scan, and a CT scan, took X-rays and cannot find anything wrong!"
Doctor: "I did some research online and came across a similar case - severe headache across the forehead and down the left hand side of the face. They managed to cure that."
Man: "Tell me how, doctor, I cannot go on like this!"
Doctor: "Well, they discovered that the problem actually originated in the testicles - the man was producing too many hormones and these were the cause of the headaches - but castration solved the problem,"
Man: "Castration? You mean cutting his balls off? I am a young man, I want to have children eventually, I cannot go through with that!"
Doctor: "Then I am afraid there is nothing I can do for you"

Two days later -
Man: "Doctor, I have thought it over, the pain is so severe I have to get some relief so I will have the operation if you are sure it will cure me"
Doctor: "Well, it worked for that other young man, so I am sure it will for you too - I can actually do the procedure here now, if you like"

So the doctor administers anaesthetic and performs the castration, and when the young man comes round lo and behold the headache has gone!
Man: "Doctor, it is a miracle, the headache has gone - for the first time in years! Thank you so much!"

A week later he goes back to the doctor -
Man: "Doctor the headache has gone and I am so grateful, but I am suffering depression as I no longer feel that I am a man!"
Doctor: "Of course you are - just because you are missing some bits doesn't make any difference to who you are, but I can understand your concerns. Why not go away for a holiday, have some fun and you will see that you haven't changed? How about a city break in London?"

So the man heads for London, sees all the sights and starts to feel better, but decides to get a new tailor-made suit in Saville Row.
He chooses the material, and the style he would like and then the tailor starts taking measurements - when he gets to the inside leg measurement he asks:
"Which side do you dress, sir?"
Man: "Dress? What do you mean?"
Tailor: "I mean when you put trousers on which side do you place your ... er, genitalia. You see, sir, we tailor the trousers to accommodate you - most trousers you buy "ready-made" meet in a Y at the crotch, and this puts pressure on your genitals, which can give you a really bad headache all across the forehead and down the left side of your face!"