You will not be banned for what you say. (Score 2, Informative)

Xbox Live uses a 'warning system' where users can submit feedback on an abusive user (or good) with prepared comments like "Poor gameplay," "Harassing/Lewdness," "Good attitude," "Great session." After enough (and it takes quite a bit) complaints, your voice usage is banned for a month or so. When it returns and you continue, you will be be banned from the entire system for a month or so. After that, your account may be permanently bad. But believe me--no one's going to be banned for bad language.