By now, McCain's answer to every question -- "Let me just say that I was a POW for five & a half years" -- has become something of a joke to everyone except the corporate media & the Right-wing echo chamber. However, if he wants to avoid embarrassing himself further & losing the election, he should stop referring to this event in his life for one simple reason.
The only way one can become a POW -- a prisoner of war -- is to surrender, to give up, to put ones hand up in the air & hope that the humiliation of captivity is better than a fight to the death. And despite the fact that in some situations, surrendering is logically the best thing to do, one would expect every POW to be embarrassed that he did surrender -- & they are, indeed, embarrassed that they did.