If you pop onto Coca-Cola Australia’s Facebook page, you’ll get a nice glimpse of a social media marketing experiment gone awry. On Tuesday, the brand figured it would be a fun idea to ask the 736,000-plus Coke fans Down Under on Facebook to participate in a type of word-association game that quickly spiraled into the kind of humor you might see scribbled on the wall of a toilet stall in a biker bar.I first heard about this screw-up from a friend who lives in Australia. She posted it to my Facebook Wall, naturally. When I checked out the link I was really surprised to see the post still front and center at the top of Coca-Cola Australia’s Wall with 810 contributions from fans that look something like this:

It’s not just Coke’s Facebook fans who get caught up in the cross-fire. Former Prime Minister John Howard gets the same rough treatment.

Coca-Cola did warn us it was an experiment, but it’s not clear what the objective here is – let’s see how many d@#k jokes we can have scroll down our Wall? What exactly did they expect from their fans? Haiku poetry? Chris Zappone at the Sydney Morning Herald notes it’s yet another case of a big brand marketer learning the hard way (no pun intended, really) that social media marketing runs by its own set of rules, particularly when the public is asked to contribute. And the golden rule is? In social media, brands have little to no control over what fans will ultimately say.

The irony is Coca-Cola learned this lesson the hard way, back when those viral Mentos-Diet Coke geyser videos first hit the web. Or so we thought.

Learn from the digital pioneers, brands like Coca-Cola, Carnival Cruises, Whole Foods, Vodafone and scores of others. Their social media blunders – in the areas of crap customer service, plain dumb marketing or simply being caught short in a crisis – provide valuable lessons from which to shape future corporate comms policy. It all can be found in our new e-book, #FAIL: The 50 Greatest Social Media Screw-Ups and How to Avoid Being the Next One. Buy the book today on Amazon UK, Amazon or Lulu. iTunes and Nook coming soon.