Yesterday, during a conversation with a good (non-journalist) friend, the talk steered toward the News of the World scandal and the Kansas City Star’s sacking of columnist Steve Penn for plagiarism. (Full disclosure: As discussed numerous times on this site, I interned with the Star last summer.)

He was angry about the NOTW’s alleged phone hacking, while I was flummoxed as to how any professional journalist could plagiarize in this era and expect not to get caught. The ending question was the same for both of us: How could anyone be so stupid?

Fast forward to this afternoon, when the BBC posted an updated list of social media guidelines. Included, verbatim, in the guidelines is the blunt advice, “Don’t do anything stupid.”

After laughing a little, I thought, “Well, what does that mean?”

The BBC guidelines suggest that its journalists should avoid overt partisanship on sites like Twitter, that any “official” tweets should be read by at least two people, and that “official” BBC personality profiles should be kept professional at all times.

The tips were common-sense enough, almost deceptively so. Social media — especially Twitter, but theoretically any such site — is fraught with potential mistakes and lapses in judgment. In print, your words go through an assignment editor, a slot editor, a rim copy editor and a proofreader. Any flagrant stupidity is, I hope, flushed out. If nothing else, there’s time to consider words and allow anger to cool off.

With Twitter, though, it’s easy to slip in a moment of hot-headedness. In 15 seconds, you could type and post something that you’ll regret for years. Journalists have been fired or asked to resign over tweets. So have spokespeople. Not to mention political candidates and public relations workers. Whether their terminations were justified is beside the point; their employers determined that their tweets were inappropriate to the point where they were sacked.

So how can you avoid this? How can you not “do anything stupid”?

1. If you tweet for your job, I’d consider having two separate profiles, a personal one and a professional one (example: @john_doe, @john_doe_kcstar). Many journalists I follow on Twitter have just one profile for both personal and professional use, and that’s fine. But it’s something to think about, especially if you’re new to Twitter or unsure about your company’s precise policies.

2. If you keep one all-purpose Twitter account, it’s worth using up biographic real estate to cover your butt. “RTs are not endorsements.” “A follow is not an endorsement.” “My opinions are my own.” Obviously this won’t be enough to save you if you’re flagrantly misusing Twitter, but it does create a conscientious wall between your personal views and your professional ones.

3. Avoid getting into Twitter spats with readers. I see far too many writers (a lot of them columnists) engaging in prolonged insult-fests with members of the public. A reasoned response or even a tart one-liner is probably fine. But it just looks childish if your feed is clogged with a back-and-forth argument. The longer it goes on, the angrier you’ll get and the likelier it is that you’ll say something stupid. Remember, if you’re arguing with an idiot, so is he.

4. For the love of all that is holy, know the difference between normal tweets and direct messages. Let’s not say that Anthony Weiner’s political downfall was in vain, yeah?

5. If you retweet anything — especially if it’s a photo or a link — make sure that it says or displays what you think it does. Never retweet anything blindly (I admit I’m guilty of this when I’m in a hurry). If you think you’re linking to a Times story, make sure you’re linking to a Times story. Nothing is more annoying and embarrassing than unknowingly retweeting spam or something else that’s inappropriate. In the same vein, if you’re following people and reporting on their tweets, make sure that what you’re following are their real accounts, and not parodies.

6. The adage that it’s better to be correct than first is true with Twitter as well. Before you fire off a tweet, edit yourself. Without a copy desk, the responsibility is even more on you to make a good decision. Let it sit for a few minutes, however long it takes. Is it something you’d say face to face with someone? Would you include it in a print or Web story with your byline? Does it target anyone based on religion, race or gender, even in jest? Does it contain profanity? When in doubt, don’t hit send.

Twitter at this point is an absolute necessity for journalists, politicians and most major companies, but it can be a double-edged sword. So tweet smart.