You take your eyes off the political scene and go on vacation and what happens?  John McCain's hand becomes news — a gift to those who study non-verbal communications, and a lesson in the limits of body language 'reading'. 

What was the fuss about?  McCain was asked an embarrassing question about why many health insurance policies cover Viagra and not contraceptives.  He hesitated for 8 seconds before giving a fumbling answer.  While he was hesitating, his hand shot up to his mouth and covered it.

What did the hand signify?  Not, as the commentary has suggested, that he was trying to keep himself from lying.  Children do that, not adults, and especially not adults as comfortable with evasion as seasoned politicians.  And that's the wrong way to think about hand gestures.  They usually don't convey specific meanings like that; rather, they spring from emotion. 

What happened in that moment was that John McCain had a strong emotional reaction to the question.  We put our hands to our faces when we are thinking, and to cover our mouths when we're shocked or appalled.  John was shocked or appalled by the question, and then he started thinking.  The whole process took 8 seconds, which suggests he was quite flummoxed. 

Why was he appalled?  That's where it gets interesting, and body language along can't tell us.  We need to know something about the man.  Was he appalled because he's a prude?  Unlikely; he's a former Marine.  Was he shocked because he was afraid his use of Viagra was going to become news?  Possible, but that's sheer speculation.  Was he appalled because it was a 'gotcha' question and there was no good answer immediately in sight?  Most likely. 

All body language can tell us is that McCain had an emotional reaction strong enough to last 8 seconds.  That's significant, because 6 seconds is the average length of time people in conversation or discussion will let a silence lapse (try it yourself).  That means that his emotions were stronger than average.  Or perhaps that he was just tired and slow on the draw.  It's a great lesson in the insights and limitations of reading body language.