The Bad Astronomer and Cocktail Party Physics talk about how to deal with purveyors or believers of woo in social situations.

I suppose that I've been lucky that most of my family and friends don't really fall for stuff like astrology, aliens, homeopathy, ghosts and whatnot. At least, I think they don't. If they do, they keep it to themselves, which is fine by me. The worst I've had to put up with is one friend who insists that the Moon Illusion is anything but and optical illusion. If that's the worst I have to deal with, I'll consider myself lucky and go on my merry way.