You should probably have a sense already of whether your Twitter account might get you in trouble at your job. Like, complaining about the stupidity of your boss on social media? Not the most excellent idea! But if for some reason you are just not a very reflective person, you can use FireMe! to figure out if your tweets are going to get you canned.
FireMe! mines Twitter (either your personal account or Twitter as a whole) for incriminating work-related tweets. So go to the site's homepage, and you'll see a public shaming of people tweeting things like: "My boss is an idiot," and "I hate my job." There's also subcategories you can look at. "Horrible Bosses," (standard hate) "Sexual Intercourse," (just use of the F-word, pretty much) and "Potential Killers" (people hopefully kidding about shooting their bosses) are included. If you enter your own personal Twitter account, it'll calculate your odds of getting fired if your boss sees your account.
But best of all, there's a leaderboard for All-Time Most Fireable Tweeters. Just be careful clicking on those. Some of the language coud get you in trouble at work.