This second one is another case of that. It's this idea that in August, that Mars is going to be remarkably close to Earth. You know, it'll appear larger than any times in our lifetimes. Something like that actually happened, but back in August of 2003. So, it's long since outdated.

There are things that are sort of seasonal. Like sort of household remedies for repelling mosquitoes, or treating bee stings. Those tend to pop up every year around this time of year. Or the idea that "In God We Trust" has been omitted from President dollar coins.

DP: Is that true?

DM: No. We actually have some of the coins over here. I had to get them to prove the point.

But it's continually spread by people who've never actually seen one of these coins, who are unlikely ever to encounter one of these coins, but still urging people not to accept them because they don't say, "In God We Trust."

DP: What's driving people to pass this stuff on?

DM: A lot of it is just people's desire to do good. They think they're being helpful by passing along something -- a piece about a missing child, or warning you about some sort of crime that you might fall victim to.

Some of it is just people looking to show off. "I'm smart. I know this and you don't."

Some of it is attempts to prove other people wrong about things, usually of a political nature. A lot of things that are truly urban legends: things that have narratives, that have plots, and morals. They're often a way that people encapsulate and pass along fears and anxieties. A lot of what we see is directly related to what's going on in the world.

They're also tacit ways of expressing or reinforcing prejudices. Maybe a crime rumor that has to do with gangs or Mexicans. And it's -- "Well, I'm not saying this about whatever group. It's the story I heard says that they're doing whatever." It's sort of a camouflage.