Why do some people say “Excuse my French” before/after they curse? Did the French historically have dirtier mouths than other Europeans?
Or is it just the British who thought so and thus came up with the phrase?
This explanation could be total B.S. (pardon my French) but this page
http://members.aol.com/MorelandC/HaveOriginsIndex.htm
says it does indeed come from the English thinking the French are vulgar louts.
I would tend to believe that cite as the French also have expresions using the English that are not too complimentory either. “Filer a l’anglaise” (pronounced “feelay” kind of)means to run away in a cowerdly manner.
d (french guy)
My personal favorite French expression is “être de Birmingham” (to be from Birmingham) meaning…to be really, really bored.
Corr
It comes from a long history of using the word “French” to indicate vulgarity. The stereotype of the French people used to be (and I guess to an extent still is) one of a sexually oriented (and thus, in the past, deviant) crowd. Therefore, the term “French” was attached to anything vulgar or overtly sexual. An example would be “French postcard”, an early term for pornographic pictures.