I got censored there, sorry, I didnt say a really bad word, I said Dam*....apologies

I just say "We don't say that in this family. I don't want to hear you say it again."
About other families in general :- "Fred might be able to watch that film.... but you can't because you are 10 and that film is a 15.... and it's been given that certificate because it's not suitable for your age. It's too violent and you wouldn't enjoy it."
As a parent, all you can do is set your won standards and stick to them. You will find that some perfectly decent families place their rules in different places to yours... that's fine, you just have to stick to your rules and whats important to you. My children go to bed later than many of their peers (none of them need loads of sleep), but I don't allow them to use bad language. My children have to learn to deal with that.
Good luck and stick to your guns.