Although it's more likely than not that they'll stay on the secured grounds of their rented estate, it's not impossible that if you're on Martha's Vineyard at the same time that you could bump into the first family. Maybe Mrs. O will be taking the girls to Mad Martha's for an afternoon ice cream. The president might hang out and watch as his daughters try for the brass ring on the Flying Horses. Or the first couple will drive over to A Bunch of Grapes to stock up on beach reading or bring home art from Cousin Rose Gallery. The possibilities are infinite.

But one thing is certain: the first family came for the same reason many of the island's other summer residents did: to rest, relax and rejuvenate before they plunge back into work and school.  So if you bump into them:

Smile and wave.

If they stop to shake hands, by all means, shake back. Feel free to wish them good luck, godspeed, whatever.

Don't engage in a long, drawn-out debate about the things he's trying to leave behind in Washington. (Vacation, remember?)

If they let you take pictures with them, do it quickly.  Don't ask for retakes cause your eyes were closed or your hair wasn't rightthere are probably other eager people behind you.

Finally: Let them move on. If they were kind enough to stop and chat, it means they interrupted their journey (or meanderings, after all, they're on ... what? Vacation!) and they'd like to get to wherever they're going.  So let them.

That way, you'll both have pleasant memories of the encounter.

Karen Grigsby Bates is a Los Angeles-based correspondent for NPR News and co-author, with Karen Elyse Hudson, of The New Basic Black: Home Training For Modern Times (Doubleday).

is a Los Angeles-based correspondent for NPR News and co-author, with Karen Elyse Hudson, of The New Basic Black: Home Training For Modern Times (Doubleday).