I was recently watching iCarly, a show I usually only watch while babysitting. The episode I was watching was iKiss, where Carly's friend Sam told everyone watching the iCarly web show that their other friend, Freddie, had never kissed anyone. Freddie gets extremely embarrassed and stops coming to school or talking to anyone. Carly gets angry at Sam for humiliating him like she did, telling her that no matter how she apologizes to him, nothing will work - she's already done the damage and spread the word. (Watch the episode to find out the resolution!)
This concept can also go for cursing. Once you've said a bad word, you've said it; there's no way to take it back. This isn't to say that if you say one bad word in you're life, you're doomed to being thought of as someone who curses. However, it is a reminder to always really guard your mouth. You don't want people thinking that you curse often, and if you let words slip more than a few times, people may start thinking so.
This is also something to be remembered when gossiping, too. While Bleep!'s message is primarily against cursing, anything relating to bad language is also in Bleep!'s general domain. If you say something against someone, spread a rumor that's true or false, anything bad about anyone else, there's no way to take it back. It will always be out there. Think about what you say before you say it: is it something you want to be floating in people's minds forever?