According to a 2009 study by Internet security firm Proofpoint, 8 percent of companies with over 1,000 employees have fired someone for their social media actions — a figure that is double what was reported in 2008. Yet it probably comes as no surprise that Facebook firings are on the rise. Cases of employers firing employees for social media slipups have been consistent in the news over the past few years.

Just in case you need a refresher of what not to say online, here’s a timeline of 12 ridiculous examples of how Facebook can get you fired.

1. November 4, 2008:  New England Patriots cheerleader Caitlin Davis was cut from the squad over controversial pictures that were posted on her Facebook page. Then eighteen-year-old Davis was at a Halloween party when she posed for photos with a passed out man who was covered in graffiti, including swastikas, anti-Semitic remarks and profanity. Davis was fired from the squad after the pictures appeared on various Internet websites and caught the attention of the Patriot’s management team. She had been the youngest cheerleader ever to make an NFL squad.

2. February 26, 2009: A U.K. teenager was fired for calling her job “boring.” According to The Daily Mail, Kimberley Swann posted comments like “First day at work. Omg (oh my god)!! So dull!!” and “All I do is shred holepunch and scan paper!!!” [sic]. Swann was canned after her boss discovered the comments.

3. March 9, 2009: Dan Leone, a stadium operations employee for the Philadelphia Eagles, was fired for voicing his opinion on the team’s trading practices via Facebook. Leone reportedly updated his Facebook status with “Dan is [expletive] devastated about Dawkins signing with Denver … Dam Eagles R Retarted!!” [sic].

4. April 27, 2009: A Swiss woman was let-go after calling in sick, and then logging into Facebook on her “sick day.” Apparently the women had a migraine and called out of work because she thought the light from a computer would bother her and she needed to lie in a dark room. When her employer caught her surfing Facebook, it was presumed that she was indeed well enough to sit in front of a computer, and she was let go.

5. April 28, 2009:  A Minnesota nursing home employee was fired after rumors spread that she had posted photos of herself with nude patients on her Facebook page. Though no nude pictures were found, the employee did have pictures of herself with clothed patients, which violated the home’s privacy policy and lead to her termination.

6. August 27, 2009:  Ashley Payne, a Georgia high school teacher, was forced to resign after the local school board came across pictures of her sipping beer and wine. The pictures, which appeared on Payne’s Facebook page, were from a vacation she had taken that summer, which included a trip to the Guinness Brewery in Ireland. Payne was quoted as saying “I did not think that any of this could jeopardize my job because I was just doing what adults do and have drinks on vacation and being responsible about it.” She sued the school district last November.

7. February 11, 2010: South Carolina firefighter and paramedic Jason Brown was fired for creating a three minute long animated video and posting it on Facebook. The video, which showed a cartoon doctor and paramedic responding to an emergency in a hospital, was meant to be a spoof, according to Brown. However, his department didn’t find the video to be funny, calling it “an embarrassment,” and Brown was fired.

8. March 3, 2010: Gloria Gadsden, a professor at East Stroudsburg University in Pennsylvania, was fired after updating her Facebook status with things like “Does anyone know where I can find a very discrete hitman? Yes, it’s been that kind of day.” The school said it was being overcautious due to the then- recent Amy Bishop case, in which the University of Alabama professor went on a shooting spree and killed three of her fellow professors.

9. May 17, 2010: North Carolina waitress Ashley Johnson was fired from her job at a Brixx pizzeria after posting a negative comment about two of her customers. Johnson called the customers — who left her a $5 tip after sitting at their table for three hours — “cheap.” Though she did not mention the names of the customers, Johnson did include the name of the pizzeria in her post. A few days later, management called her to tell her she was fired for violating the restaurant’s social media policy.

10. May 24, 2010: The city of West Allis, Wis. fired a veteran police dispatcher of 21 years over a status update. Dana Kuchler was terminated after posting that she was “addicted to vicodin, adderall, quality marijuana, MD 20/20 grape and absinthe,” on her Facebook page. Kuchler, who said the post was meant to be a joke, filed a lawsuit against the city.

11. June 10, 2010: Five California nurses were terminated after it was discovered that they were discussing patient cases on the site. The situation was investigated for weeks by both the nurses‘ employer (Tri City Medical Center in San Diego) and the California Department of Health, before the nurses were fired for allegedly violating privacy laws.

12. June 21, 2010:  A Pittsburgh Pirates’ mascot was let go earlier this summer, after posting a comment about the team’s choice to extend the contracts of two of its managers. Andrew Kurtz, 24, was fired within hours of posting the comment “Coonelly extended the contracts of Russell and Huntington through the 2011 season. That means a 19-straight losing streak. Way to go Pirates,” to his Facebook page.

Whether you think the above are examples of employees exercising free speech or simple stupidity, it seems as if Facebook postings are fair grounds for termination at many employers. With that in mind, post at your own risk.

Kaitlin Madden is a writer and blogger for CareerBuilder.com and its job blog, The Work Buzz. She researches and writes about job search strategy, career management, hiring trends and workplace issues. Follow @CBForJobSeekers on Twitter.