Plenty of national food service companies have been eager to wade into the social media world as a way to engage and recruit customers. Restaurants, large and small, have pumped up their online presence in recent years and the internet has become a very important medium for advertising.

But social media also has a dark side, because once you throw your brand out into cyberspace, anyone can praise it. Anyone can also tear you down. Take Jack-In-The-Box as an example.

The national chain ran a Super Bowl ad in 2009 that featured their long-time mascot, Jack, getting hit by a bus. Jack-In-The-Box followed the ad up with a social media marketing campaign that allowed users to post get well cards for Jack. The chain leveraged several social outlets, including Twitter, Facebook, and Flickr. Thousands of people responded, and a good portion were great for brand-building.

However, a significant percentage were vulgar, brand-bashing, and downright offensive. In the “old days” (read: anything more than 3 years ago) relinquishing power over what could be said publicly about a brand was pure marketing sacrilege.

But progressive marketers these days have recognized a couple key sea changes, especially as the Millennium Generation gains buying power. First, people 30 years old and younger in this country have been bombarded with advertising since birth. They know when they are being pitched and they are likely to be skeptical. Second, anything that lacks authenticity is Dead On Arrival, and a waste of marketing dollars.

Hence Jack-In-The Box’s willingness to let consumers drive their campaign, even if it meant allowing Jack to get beat up in the process. In the end, the ultimate authenticity is a surrender of control over a brand. The most authentic marketing is word-of-mouth, and in an era of unprecedented connectivity, word-of-mouth can travel at lightning speed.

Campaigns like “Get Well Jack” are ways to harness the powerful, if unpredictable, world of electronic communication. Just be ready to experience the dark side of social media marketing, where brands are passed through the ringer by anonymous pranksters. Luckily, most brands come out the other end bruised but truly “authentic.”

Your restaurant’s brand, no matter how small, operates under the same rules as Jack-In-The-Box. The difference is one of degree only. You pour your heart and soul into your business, and it can be very difficult to watch others bash it online. In the end, however, you stand to benefit by allowing customers to drive the conversation about your brand. Ceding that control can be a scary but also liberating experience.