Y: Don, your eyes are all swollen and puffy. Have you been crying?
D: (INDIGNANT) Of course not, Yael. I'm a man!
Y: Are you sure you haven't been watching soaps again?
D: No. These tears that you're seeing are the very same ones that keep our eyes moist and comfortable, and wash out bits of dust and debris.
Y: Hmm! are you sure? Those basic tear secretions are produced in the conjunctiva, the membrane that coats the entire surface of the eye.
Y: So these basic secretions don't overflow like the tears associated with emotional crying. Those tears are produced by the lachrymal gland, located in the upper, outer corner of our eyelids, and not only are they much more watery than basic tear secretions, but there are usually so many of them that they overflow and spill down your cheeks and drain through tiny ducts into your nose.
D: Not my nose—I don't cry.
Y: I didn't mean you personally.
D: A friend of a friend, but not me—has been crying. Why would his eyes get all puffy?
Y: Like yours are now?
Y: Well, because emotional tears are more watery, they're less salty than basic tear secretions and the tissue in your eye. So, through the process of osmosis, the water moves into the saltier ocular tissues, which makes them swell up. And then there's all that furtive eye rubbing your "friend" does to hide his tears, which inflames his eyes even further. Still, even though it looks bad, the puffiness and irritation will eventually go away.
D: Well, that was easy. I guess I'll go back to watching "Love Story."
Y: Don't forget the Kleenex.