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It all started with an innocent "tweet"--a post to the micro-blogging site Twitter. Connor Riley, a 22-year-old pursuing her master's degree in information management and systems at University of California, Berkeley, wrote:

Cisco employee Tim Levad saw the post and responded with his own tweet:

That exchange exploded into what is now known as the "Cisco Fatty" incident--other Twitterers picked up the posts, and soon the Internet was all atwitter about a prospective employee who squandered a job opportunity in this dire economy for saying something stupid online. Riley ended up writing a post on her personal blog apologizing for her tweet, explaining that she was being sarcastic and that she'd actually already turned down the offer.

OK, so no real job loss here, but the incident begs the question: Can social media get you fired? Ask Dan Leone, and the answer is a resounding "yes." Leone, a Philadelphia Eagles employee, was bummed when Eagles player Brian Dawkins signed with a rival team. So he posted his state of mind on Facebook:

Days later, he was canned by the Eagles.

What you post online, whether it's on your personal blog or at a social networking site, matters. (Who can forget Heather Armstrong, who got fired several years ago for writing about her job on her personal blog, Dooce.com? The episode launched the phrase "getting dooced" to mean being fired for blogging about work.) But I think social networking sites like Twitter and Facebook pose a bigger threat, because it's easy to get lulled into the feeling that we're just posting comments for our friends' consumption. I don't even think employing the most stringent privacy settings--like having your profile or thoughts available to "friends only"--is much of a safeguard. It just takes one person to create a screenshot of something you write that could haunt you for life. So next time you post something online, err on the side of caution. Assume the everyone in the world can read it--and would you really want them to?