Claims “Steve Riley” in his amazing presentation at TechEd called “SEC285 - Defending Against Layer 8: How to Recognize and Combat Social Engineering” I can't express to you how much you want to watch this presentation.
I'm literally scared now to use ATM machines, or to give my credit card to waiter, or to even talk to a woman now. Anyone might be a social engineer trying to (ab)use me. I think it's safer for me to just get rid of all my ties to technology and live on a farm out in oregon (hey, they've got great wine out there). That... or I'll just be a hell of a lot more careful now with things that I fnd important.
The idea is simple (and rationally I've always known it), but it's scary to realize how every system out there is only as strong as its weakest link. And that weakest link is almost always going to be a person. Every person can be influenced, and so the security of a system can always be influenced as well.
I'd say more, but you should just watch this yourself and then send this out to your friends. You'll be really glad you did.