The Imus show was pure guy play in the tradition of humor as channeled aggression. Poking fun -- laughing at each other and oneself -- is one of man's more charming instruments of survival. When guys spout off hostilities in an environment of mutual trust -- the sort that evolves from team play and common showers -- nobody gets hurt.

Humor can also be a form of peaceful rebellion, in this case against a sometimes too-precious culture. When you can't say anything, you want to say everything. "Just say no"? Just say bring it on in copious quantities of obscene excess. Yesssssss!

The reflex to do precisely what one is not supposed to is as American as the Boston Tea Party. They say we can't or must, and we say, "Yah, right."

Imus has been saying "Yah, right" for a long time. But this time, he said it to the wrong people, picking on individuals who weren't in on the game. Who didn't consent to the rules. Who were not one of the guys, but young women who don't belong to the culture of boydom.

Towel snapping is only fun and fair, after all, if everybody has a towel.

The success of both Sharpton and Imus, despite sometimes contemptible behavior from both, was owing precisely to their having served a constituency that feels beleaguered.

But when one's audience is a marketplace of misery -- when one's success depends on the perpetuation of victimhood -- the groove eventually becomes a rut. Sharpton's search for justice got bogged down in reverse racism; Imus' humor got mired in gratuitous insult.

Captured together in the same frame last week, Sharpton and Imus -- media stars fashioned by anger and sustained by self-absorption -- were cultural doppelgangers come face to face.

They not only mirrored each other, but also, like opposites, they canceled each other out.