Imagine walking into a meeting and encountering not just your current co-workers, but all your colleagues and managers from jobs past, along with your spouse, your drinking buddies, and, off in a corner, your adolescent son, busy telling your boss how many hours he logs in every day playing Grand Theft Auto.
If you're anything like the 200 million users on the burgeoning social network, you probably didn't give enough thought when you first signed on to which friend requests you accepted, or whom you invited via the Friend Finder. Now you've got a dangerously random group of friends and friends-of-friends sharing - and over-sharing - information, sometimes without your even being aware of it.
The 'he told two friends, and they told two friends' syndrome can be embarrassing in your personal life, but potentially much more serious in the world of work.
Even if you're careful in posting work-related news in your status updates and comments on others' walls and feeds, are each and every one of your friends as cautious as you are? One mate writing 'How did the redundancies go down?' on your wall is enough to cause havoc in your office - particularly if layoff day hasn't yet happened.
Even more troubling: the online behaviour of those who report to you, who, demographically speaking, are likely to be both more enthusiastic and less discriminate in their use of Facebook and other social networks. "Younger people are using Facebook on a quasi-professional basis to build stronger relationships with people," says Michael Argast, director of Global Sales Engineering at security vendor Sophos. "That means they're sharing a lot of information with a lot of people on a regular basis."