I give good advice. Really, I do.

When I was a PR senior executive, I often told my assistants they needed to watch the tone of their emails to clients, editors and colleagues–even more so if they were feeling peevish. I suggested to keep the jokes to themselves as well as the wry comments, political views or simply sharing too much personal information so as not offend anyone. Sounds good, right?

Yet because I have this certain arrogance there are times I believe I’m above this and I can blurt out or type whatever comes to mind. In other words, I don’t take my own advice and Facebook is the proof of the pudding.

What did I do to get in trouble? Exactly what I told my former assistants not to do. I was having a bad day, feeling peckish and snarky, and I commented on a photograph a friend had posted. My attempt to be clever and poke fun at myself backfired. I also managed to dig my hole deeper after a text message exchange.

Although I emailed a sincere apology, I feel I’ve become persona non-grata. If this had occurred to someone else I would have recommended she pick up the phone and speak to the offended party after that first text message. The tone in the voice would have been interpreted differently and the exchange would have gone in another direction.

As much as I enjoy the Facebook virtual water cooler, I have to remind myself that even though I interact with so many people and I have 200+ “friends,” the rules of written communication also apply to social sites—even if you know the person and you think they understand your jokes.

So heed this advice: Use the filter and your Friends list will remain unscathed.