This maybe?
'Have you ever been in the grip of the friendly but overpowering handshake? I'm not talking about the guys that grind your bones together in an attempt to cause pain, but the guys with the huge paws or the guys who don't know their own strength, or the guys who try to intimidate others by simply applying a vise-like grip when they shake hands. You know the guys. Typically big guys with huge hands, an overbearing laugh, and most likely a tiny phallum bway bway.
Here's the fix. As you grip hands, extend your index finger of your right hand so that it presses lightly against the inside of their right wrist, instead of curling it under the palm of their hand with the rest of your fingers.
That's it. Now, try as they might, they can't squeeze so hard as to cause you any pain at all. They can really squeeze hard and they will get no wince or grimace from you; it won't hurt at all.
Give it a try. You'll find the sweet spot quickly working with a partner, and then you can do it whenever you like.'
http://www.martialtalk.com/threads/a-fix-for-the-hand-crusher-handshake.120835/