For late-night TV writers, here's the formula: One controversial figure plus another equals comedy gold. So when Alaska Gov. Sarah Palin goes to a New York Yankees baseball game, you add juiced-up playboy Alex Rodriguez and you get ... uh oh ... comedy base metal. David Letterman, or one of his writers, made the mistake last week of not noticing that the former vice presidential candidate had attended said game not with her notorious 18-year-old daughter, Bristol, but her 14-year-old daughter, Willow. So when Letterman quipped that Palin's 'daughter was knocked-up by Alex Rodriguez' during the seventh inning, he thought he was playing by the accepted rules -- Bristol, an adult single mom who has made herself a public figure, has been the butt of far raunchier jokes on late-night TV. But making a sex joke about a minor girl isn't edgy, it's over the edge. We come to unbury Letterman, not to praise him; it would have been a tasteless joke even if it had hit its intended target. But the reaction to this comedy blunder has been irritatingly disproportionate, with Palin going so far as to say that Letterman was promoting statutory rape. The TV comedian is partly to blame for the firestorm, after he fumbled through a patently insincere 'apology' last week. He issued a genuine one Monday night, but that still wasn't enough for conservative activists, who held a rally Tuesday at the New York studio where Letterman tapes his show and are demanding that he be fired. The brouhaha has been a godsend for Palin, getting her face back on TV screens and her name back in the headlines as she ponders her presidential prospects for 2012; it also can't hurt her fundraising efforts as she passes the hat to repay legal fees incurred in the 'Troopergate' scandal. Letterman has benefited too, with soaring ratings. The losers? Everyone else. After emerging from a presidential race in which the taking of umbrage was a constant theme of both campaigns, with each accusing the other of a new outrage seemingly every day, Americans should be thoroughly sick of manufactured controversies. Until they stop paying off for their creators, though, we're likely to suffer through a lot more of them. 