Facebook Costing Jobs?

I used to work at Ruby Tuesday, and had a friend that quit there right before they closed down. The reason: a facebook post. She had a stressful day at work dealing with the cooks and put something along the lines of giving the cooks anthrax as a Christmas present as her status update. Obviously, this was a joke. Seriously, who has access to anthrax? Well anyway, the kitchen manager decided to take this as a literal threat to his life and told the General Manager, who then brought the issue up with my friend. By the way, my friend had been there for about 4 years longer than this kitchen manager, so you can understand her being upset over the General Manager giving her a "talk" about this issue, that wasn't even really an issue in my opinion. So, long story short, she quit over the incident. This shows how social media can have a negative effect on your life.