I'm not a fan of foul language in any tongue, and even less appreciative when people feel the need to excuse themselves of it yet continue anyway. In English many people have the unfortunate habit of excusing their poor linguistics by passing the blame. Somehow or another, English speakers have developed the expression pardon my French, presumably a hold over from a former era when well educated English people might have known a good deal of French and understandably sometimes wanted to use the choicest adjectives from it in their English communications. However those days are gone and the people who use it most are those least educated and it has become a prefix to the least choice English vocabulary.
My question is, do French speakers have any similar customs of excusing bad language before they utter it, and are there any similar idiomatic expressions that pass the blame for less polite vocabulary on to another people or language?