The phrase très sale is common French slang for something very dirty or hardcore, and the M6 tag points to a television broadcast as the recording source for this short clip. Its exact programme context is not widely documented, so the sound has spread mainly as a standalone reaction rather than as a quoted scene. Short French voice clips like this travel easily on soundboards and in edits because they are instantly quotable, work without subtitles for many viewers, and can be dropped over unrelated messy footage to create the same joke.