Popsugar reports that Jessica Simpson and her man-piece, Eric Johnson, ran into Simpson’s ex, Nick Lachey, and Vanessa Minnillo while dining out in LA last night. The report says that the two couples ate next to each other for hours.

No doubt they were the epitome of etiquette and good breeding. But what does that mean, exactly? What is one to do when one sees one’s ex?

Well, here are a few suggestions:

Keep conversation light. The further you go into anything meaningful, the more likely it is that you’ll say something you regret. I.e.: “This is my new boyfriend…yeah, it’s been about a month….no, I guess that’s not very long…I mean, who knows if this is long term? Not that I’m not having fun with him…not that it’s just about fun…not that I don’t want to get married…never mind.”

Don’t be afraid to end the conversation. Even if you end it abruptly, it’s a lot better for him and his entourage/date to be left saying, “wow, she left quickly,” and wonder what important thing you were going to, then for them to be left saying, “wow, that was awkward.”

SMILE. I’m taking advantage of international caps lock day to make my point, here. I don’t care if you’re choking back tears, or rage, or even ennui. Smiling always makes you look like the bigger person. And if you don’t feel it, fake it till you make it. You will be really, really glad you did.

Of course, these rules don’t apply if your ex really did you dirty. In that case, you are well within your rights to ignore them, leave the restaurant (subtly), or even — if it was really bad — make eye contact and then deliberately move on. Touche.