case hardened

steely resolve, resolute mental grip on a situation, where welding equipment (or LSD!) would be the only thing one could use to make it budge!!

case hardened businessman

case hardened virgin

case hardened politico (liberal OR conservative!)

he is a case hardened businessman, he'll never budge on that price!

shes' a case hardened virgin! you'll never 'crack that crotch'
hes' a case-hardened conservative