Photo: Albert Watson for RollingStone.com

Here's one of my biggest pet peeves: You're arguing with your friend—or your partner or your mother or your boss—and you get your feelings hurt. When your friend realizes she's gone too far, instead of apologizing, she says, "I was just joking." LOL?

Actually, no. Jokes should not be cheap Groucho Marx glasses you use to disguise heat-of-the-moment insults. Humor, when deployed correctly, doesn't just lighten the mood; It can change the whole tenor of a conversation for the better. Real jokes offer an opportunity to say something you believe in a new way or to see something someone else believes in a new light.

This is something Jon Stewart understands. In an excellent cover story in this week's Rolling Stone, he explains how he and his team keep The Daily Show, which won its ninth Emmy on Sunday, from becoming too preachy, and in the process he also explains why so many of us admire him: "The key is not to contrive it—don't bring the same level of indignation to things you don't feel. As long as you keep it as honest as you can to your own feeling, then you hope it doesn't become a pure parlor trick."

At the risk of sounding overly preachy myself, shouldn't we all aspire to stay as honest as we can to our own feelings whenever we communicate? Stewart doesn't insert levity into a conversation because he doesn't take it seriously, he does it because it's a way to express serious things clearly. Or, as Oprah put it when she interviewed Stewart in 2005, "You say what everybody else is thinking but can't articulate, in a way that makes people laugh. That's a gift."