BORDEAUX, France—When you're studying at a language school like the one I’m at in Bordeaux, you get used to people coming in and out of your life with the coming and going of each week. A Swiss guy who started here the same week as me once compared the rapid replacement of friends and acquaintances to life in general, only much faster.

The similarity is undeniable, but here, when people you've seen every day and shared many an entertaining evening with leave your life possibly forever, there's time to prepare and celebrate.

Last week was something of a mass exodus. On Friday, to celebrate the last night of nearly half the people I'd known in my two weeks here, we had a picnic on the quay next to the Garonne river, which runs through Bordeaux.

After eating, drinking, and conversing in a hesitant mélange of French, English, German, and Spanish, we gave in to the urge to dance.

Each weekend night, the city of Bordeaux hosts dancing next to the river. The style is different every night, and so is the crowd. I went once two weeks ago when it was Samba (though not real Samba, according to one of the Brazilian girls). This particular evening it was swing dancing.

Each evening begins with a tutorial of the basic steps, although some people seem to be nearly professionally-skilled already. We'd missed the swing lesson, though, so we had no idea what we were doing. We tried to mimic the steps of those around us.

Behind me there was an old man, a septuagenarian, at least, accompanied by two slightly younger women. He stood in place, waving his hands in front of him and swaying to the beat, while the women swung about with each other. Further away was a younger couple in perfect swing dance attire. The woman’s satiny dress of black and white polka dots swung perfectly in sync with her twirls. There were lots of other couples—some young ones who looked like they could be on terribly awkward first dates and some older who looked as if they probably came out to every one of these dances.

We tried to twirl and shimmy as they did. It probably didn't look quite right. While we paused momentarily to take some photos and take off sweaters, a large security guard came up to us and scolded us in French. If we weren’t going to dance, we would have to move off to the side. Hurriedly we continued to dance. We must have been pretty terrible because he came back a couple more times to tell us to move when we really were dancing. It didn't matter, though; I'd made peace with coming off like as stupid foreigner on occasion. I think we all had.