How far is too far when writing dialogue for YA readers?

I do use words like *****, slut, , ho and f. uck once. But most of the time they are used in a humorous way, and not in a threatening sense (more like gossip, if you will). My character's personality has to say these things or else she doesn't seem real. But how far is too far? I'm just sick of conservative people who don't like their 15 year old reading things like this. Teens do say stuff like this, and I don't really care if you like it or not.