After being hit by a bus in a Super Bowl TV/Web commercial Feb. 1, Jack — the grand-tete CEO mascot of Jack in the Box — emerged from his coma March 4, newly inspired. At Jack's direction, the San Diego-based restaurant chain will undertake a brand makeover this spring, including a new logo, redesigned store environments and a new corporate Web site that launched Monday.

Jack, I feel obliged to point out, is a fictional character.

You might have had your doubts if you spent the weekend, as I did, perusing the 81,000 or so get-well messages on the company's www.hangintherejack.com Web site. Although the vast majority of messages are innocuous and inane — "We love you, Jack," "I wish I knew how to quit you, Jack," etc. — a fair percentage are darker, weirder and potentially quite embarrassing for the company, which has 2,170 restaurants and more than $3 billion in annual sales.

Jessica Gallardo in Maine writes: "We so totally love you!!!! Defeat death!!! We would have sex with a mullhawk gorilla & the hobo under the sewer for you. We love you."

O-kaayyyy.

Alexut in Utah: "Jack in the Box killed people. They have poor sanitary habits and spread disease across the nation. Plus it's disgusting food."

Also in Utah, Ello Poppett: "... JACK GET WELL AND KILL ALL THE MORMONS ..."

And of course a thousand variations of "Jack sucks!," which is a less than optimum take-away from a marketer's perspective.

What's going on here? Call it the search for authenticity.

The six-week Hang In There Jack campaign (by Secret Weapon Marketing, Santa Monica) was a remarkable 360-degree social media event that mocked even as it exploited the power of YouTube, Twitter, Facebook and Flickr. Along the way, it leveraged irony to the breaking point with "viral" cell phone and faux-paparazzi videos, ring tones and texting. Among the crowd-sourced content were 27 get-well videos from fans, some quite brilliant.

"We were amazed, really," says Jack in the Box's vice president of marketing, Terri Funk Graham. The videos have garnered more than 4.8 million views. Graham estimates that to score the same number of impressions with traditional media would have cost three times as much (she would not say how much the total campaign cost). "Given the overwhelming amount of response and engagement, we feel we've hit a home run," Graham says.

And yet there's huge risk in throwing open company-sanctioned social media to the great unwashed, unlearned public — or, if you will, the troll-ospere. Just ask Skittles. Earlier this month, Skittles launched a home-page redesign that centered on Twitter. Any tweet including the word "Skittles" was instantly transported to the brand's online front porch. The hope, obviously, was that the candy's fans would riff and rhapsodize about Tasting the Rainbow, and for a few hours, they did. Within hours, however, Skittles' Twitter feed was vandalized by key-stroking hooligans who proceeded to rain down obscene, racist and generally obnoxious tweets on the site — hundreds an hour. Skittles, part of the Mars empire, undertook a hasty reorganization, sticking the Twitter feed under a much less prominent "Chatter" button.

The Skittles incident has become instant lore for social media marketers. And the lesson seems to be this: As eager as companies are to harness the marketing power of Web 2.0 — more than 1,000 companies now have social media outlets — Web-savvy users are a deeply cynical and hard-bitten bunch, having been marketed to since the instant of birth. A company that appears to "brand-jack" social media will likely incur the revenge of the nerds. For social media to be effective, says Mark Avnet, a professor at Virginia Commonwealth's Brand Center, it has to be reasonably transparent and unmediated, even anarchic. "It has to have authenticity or it loses its social currency," Avnet says.

And that means allowing your brand to be taken over at times by lunatics.

The Web teams at Jack in the Box and Secret Weapon knew what was coming and braced themselves for the onslaught of trolls. "For the social media portion of the campaign to be successful, we knew we needed to step aside and let consumers drive the online campaign," Graham says. "While we monitored the postings and videos on the Web site, we only removed messages that were vulgar or included profanity."

Or at least they tried. There are still plenty of messages such as Muzzi's "Your food makes me poop." Jack may wish he were still in a coma.