French
excuse (or pardon) my French used to apologize for swearing. informal
☞ French has been used since the late 19th century as a euphemism for bad language.
2018Isabelle GreyWrong Way Home 'Fuck.' Colin threw himself back in his leather executive chair. 'Excuse my French.'
take French leave make an unannounced or unauthorized departure.
☞ This expression stems from the custom prevalent in 18th-century France of leaving a reception or entertainment without saying goodbye to your host or hostess.