Mr Smith's back pain.

A man (let's call him Mr Smith) goes to the doctor with terrible back pain. It's keeping him up every night and leaving him in tears during the day. The doc runs some tests and breaks the bad news,
"Well Mr Smith, we've found the source of your problem. You see, your testicles are pressing against the base of your spine and that pressure on your spinal column is what is causing your back pain. The only solution is to chop off your testicles". Mr Smith was obviously distraught but he couldn't face another day of agony so he decides to go through with the procedure.
A few weeks later, Mr Smith, still feeling awful about his new ball-less life walks by a tailor and decides to treat himself to a new suit. He walks into the tailor and demands the finest suit that money can buy - no expense spared.
The tailor looks him up and down, pauses for a second and says "Not a problem I'd say you're a 40 long, 16 collar and a 34 chest"
"Incredible! How did you know?" said Mr Smith
"I've been doing this a long time, it's my job to know these things" replied the tailor and he scuttled away to fetch the items
Upon returning the tailor looks at Mr Smith again and says "I'm guessing you're a size 10 shoe and a 34 waist. Oui?"
"Ha!" replied Mr Smith, "Got you this time! I'm actually a 32 waist, have been most of my life"
"I don't think so. You're definitely a 34" said the tailor, "If you were to wear a 32 it would push your testicles against the base of your spine and cause you terrible back pain"