I'm full of useless knowlege like that. For example, "Saving face," "crack a smile," and " mind your own beeswax" all come from the same thing. In (again) colonial days, people would spread beeswax over their face to prevent wrinkling or acne or something (can't remember), hence "saving face." Sometimes, though, the wax would harden, and it would crack when people smiled, hence "crack a smile." And lastly, when they sat to close to the fire, which was the only way to heat your house back then, the beeswax would start melting, but it was impolite to tell another person that this was happening, hence "mind your own beeswax."
If you don't believe me, then I should at least get credit for coming up with such great answers.

Nah, those are the truth, though. If I don't know the origin, I'm usually pretty good at making them up, too. It's like my only talent. =P