Have you ever met someone who just has to be the expert on EVERYTHING? I think we all have, and we all know how annoying those people are. And how especially annoying it is to actually have to talk to them. Doesn't matter what the topic is, they know everything about it and woe to anyone who tries to correct them or - worse - disagree with them.
I happen to work with just such a person here. Actually, I worked for him when I was still in the Army which was 10 times worse. At least now when he talks to me I can just ignore him but it doesn't make him any less annoying. The most pathetic thing is when you know for a fact that he's either wrong or making stuff up and yet he still will not concede that he's full of crap.
If he wasn't such a !@#$%, I'd almost fell sorry for him. Almost.