As Mamba says, the toughest of tough will cry, but as adults we cry over pain in the sense of losing someone than we do physical pain. Kids cry through physical pain because of the shock more often than not, but as adults you just stop doing that and gasp, then swear and then go fucking bonkers.
A bloke I used to know once accidentally cut into his little finger with an electric saw. He didn't cry, infact what he did was take himself to hospital, have something for the pain and then casually ask for it to be removed rather than sewed back on. It is to this day one of the most bizarre things i've ever heard of.