In just a few short years, Facebook has revolutionized the way people socialize. The website has quickly become a household name, giving hundreds of millions of people a free and easy way to stay connected with friends, family, and colleagues across the world. But something much bigger could be on the horizon for the dot-com giant, as recent efforts could standardize a currency for ecommerce throughout the World Wide Web.

What do Nestle, Domino’s, Taco Bell, Honda, Asus, Time Warner, Pfizer, and Belkin have in common? Thanks to the Internet, they’ve all found out the hard way that there’s truth to the old adage, “You can’t un-ring a bell.” While social media can be a fantastic tool for making real connections with customers, it’s also a bit of a Catch 22—just one misstep can lead to a PR nightmare.

So, what can be learned from the social media disasters these companies have experienced? Here’s a short list of lessons to apply to your business: