Wow, Erin, I had no idea that there was so much fodder on this topic. Which pic were you referring to? There's even a theory about McCain's "tongue jut" (although clearly these photos do not illustrate a mere tongue jut):
Retired FBI agent Joe Navarro, a Bluff Magazine columnist and author of "Read 'Em and Reap," a book on poker tells culled from his professional interrogation experience, has written about the “tongue jut,” which is exactly what McCain was doing in the Colbert debate clips. Its significance?
"Tongue-jutting behavior is a gesture used by people who think they have gotten away with something or are “caught” doing something. I have seen this behavior in flea markets both in the United States and in Russia, among street vendors in Lower Manhattan, at poker tables in Las Vegas, and in business meetings. In each case, the person made the gesture – tongue between the teeth without touching the lips – at the conclusion of some sort of a deal or as a final nonverbal statement. This behavior has several meanings – depending on specific situations – but is usually associated with one of these: I got caught (taking candy from a drawer), gleeful excitement (look at what I just did, Mom), I got away with something (and I didn’t get caught), I did something foolish, or I am naughty."
Maybe. Maybe it's just gross.