Labelle's "Lady Marmalade" was a Number One hit early in 1975, popularizing the phrase "Voulez-vous coucher avec moi ce soir?," which the song repeats ad nauseam. The line, written by Bob Crewe (of Four Seasons fame) and Kenny Nolan (of "I Like Dreamin'" fame), translates from the French as "Would you like to sleep with me tonight?," fitting with the song's theme of prostitution. The song specifically takes place in New Orleans, and Labelle's version of the song was produced by the New Orleans legend Allen Toussaint.
The "voulez-vous" line is a little odd, though, given that "vous" is the more respectful version of the French terms for "you." Surely such a request need not take place on that level of diplomatic formality. It turns out the line was originally used in Tennessee Williams' A Streetcar Named Desire - also set, of course, in New Orleans - by Blanche DuBois, who might have just been using fake French to sound more sophisticated.
But a truncated version of the "voulez-vous" line appears in a song much closer to the provenance of "Lady Marmalade": Steely Dan's "Pearl of the Quarter," from their 1973 album Countdown to Ecstasy. That song - once again, set specifically in New Orleans - has Pearl in the French Quarter "singing voulez, voulez, voulez-vous." Did Crewe and Nolan hear that before they wrote "Lady Marmalade"? Could be.