Due to the “naughty” dancing of the can-can girls and the scantily clad models on 1800s French postcards, the British equated anything risqué with France. In fact, that's how the phrase “pardon my French” entered the vernacular.
DID YOU KNOW? Marlon Brando hated memorizing lines so much that he posted cue cards everywhere to help him get through scenes.
He even asked for lines to be written on an actress's posterior. (That request was denied.)