Along with youth, Don Draper’s new wife, Megan, apparently has a sharpened sense of seduction. When picking a siren song to perform for Draper’s 40th birthday during the season-five premiere of Mad Men, Megan passes over hits by American pop’s reigning songstresses in 1966—Nancy Sinatra, Petula Clark, Dusty Springfield and the like—and instead chooses a flirty French tune written as a teen confection, Zou Bisou Bisou.

Of course, the song also speaks to Matt Weiner’s own powers of seduction, as the popular series’ writer continues to ensure that musical precision remains part of Mad Men’s allure.

But what, exactly, is Megan singing? And what are the song’s origins?

Roughly translated, “zou” is a casual exclamation and “bisou” is a sweet kiss—a peck on the cheek to say hello and goodbye. So the lyrics hash out to:

Oh! Kiss kiss / My God, they are sweet! / …Oh! Kiss kiss / the sound of kisses /…Oh! Kiss kiss /…That means, I confess / But yes, I love only you!

The original version was recorded by Gillian Hills, a Brigitte Bardot lookalike who found fame as a French yé-yé girl—one of a handful of young, female European singers who catapulted yé-yé music into an international movement, popular among teens during the era. (“Yé-yé” refers to exclamations of “yeah yeah!” during rock and roll. )

“Zou Bisou Bisou was a summer smash for a 16-year-old, my first record, the summer of 1960,” Hills, who still records music and also works a visual artist, told The Daily Beast in an email.

A rendition of the song was later recorded by Maya Casabianca, an Israeli-French pop star, and landed on France’s Billboard chart in September 1961.

Loaded with saccharine and little spice, and most popular in France, Spain and Quebec (Megan’s home turf), yé-yé hitmakers—most notably Francoise Hardy and Sylvie Vartan—were pretty, with full bangs, high cheekbones and long lashes. They sang about puppy love and heartbreak through the eyes of an innocent. The pop style found its groove before French musician Serge Gainsbourg scandalized the airwaves with overtly sexual sounds, and it came on the heels of the big band swing of the previous decade.

But Zou Bisou Bisou may not have been totally unfamiliar to Draper’s party crowd. Sophia Loren sang an English version, Zoo Be Zoo Be Zoo, in The Millionairess, a 1960 film that co-starred Peter Sellers. Loren’s version uses the same tune, but the lyrics and delivery swell with a bit more sophistication. The movie was a hit in the U.K., though the American response was lukewarm.

“Eddy [Barclay, the head of Barclay Records] let me listen to Sophia Loren’s English version after I had recorded the song,” said Hills, now in her late 60s and living in London. “For some reason her version did not catch on.”

Hills said she had no idea the song would be performed on Mad Men (before The Daily Beast reached out after an early viewing), a show she calls “a very classy production.” But she did offer a prediction: “My guess: with Mad Men the song will be sultry.”