Here is the controversy between Sean Penn and the makers of the TV show “South Park,” as I understand it:

Trey Parker and Matt Stone expressed a serious political opinion in Rolling Stone magazine. Sean Penn sent them a note seriously objecting to their serious opinion. Parker and Stone made that note public then made fun of Penn for having a serious opinion.

Is that it? Have I got it? Because if so, then Parker and Stone aren’t just being hypocritical. They’re being flippant and facile – and they know better.

The two “South Park” creators, who frequently mock entertainers for expressing broad opinions, generally end each episode of their show with a broad opinion. Usually Kyle or Kevin say, “You see, we’ve learned something today …” (Cartman never learns anything), and then spins out something – common-sensical and vaguely libertarian – with which I usually agree.

So in a recent issue of “Rolling Stone,” they popped out with another one:

“… They take perhaps their strongest stand yet [the article said] – firmly against P. Diddy's ‘Vote or Die’ campaign. ‘I think just saying “Vote or Die” is a serious danger to democracy,’ Stone says, as Parker breaks into a Cartman-esque voice for a mocking public-service message: ‘Hey, nineteen-year-old who doesn't know anything – you choose.’

“ ‘If you don't know what you're talking about, there's no shame in not voting,’ Stone says finally. ‘They say if you don't vote, you can't bitch. But you can bitch all you want. This is America.’ ” Penn disagreed. After all, 19-year-olds are legally allowed to vote, and are the one who most likely fight our wars for us. So he sent Parker and Stone a note – a fairly reasonable one, except where it closes with the F word. (And this ancient reproductive term – possibly of Scandinavian origin – isn’t exactly strange fruit to Parker and Stone either. They use it seven times in the Rolling Stone article alone.) He starts by saying he doesn’t care if they make fun of him in their work. (That’s worth reiterating: Stone and Parker’s caricature of Penn on TV and in their upcoming movie isn’t the issue. It never was.) However, Penn wrote:

“I do mind when anybody who doesn't have a child, doesn't have a child at war, or isn't or won't be in harm's way themselves, is encouraging that there’s ‘no shame in not voting.’

“You guys are talented young guys but alas, primarily young guys. It's all well to joke about me or whomever you choose. Not so well, to encourage irresponsibility that will ultimately lead to the disembowelment, mutilation, exploitation, and death of innocent people throughout the world.”

Let me reemphasize, this was a private note, not a public posture. But Stone and Parker made it public, then mocked Penn for his public pronouncements. Stone also called the letter “alien logic” and told the Los Angeles Times he was actually suggesting in the Rolling Stone story that people get informed before they vote. Maybe that’s what he meant. But Penn disagreed with what he actually said.

So whether Stone and Parker want to admit it or not, they have become what they mock: They are two entertainers who are having a public, political argument with another entertainer. And it’s an argument they’re losing, by the way, because they’re trying to deny they said what they said.

You see, we’ve learned something today. You can hide behind jokes if you want. But if you express a serious opinion, someone else has the right to disagree with it. Even Sean Penn.