I have a pretty good relationship with my parents, and I cus around them. They don't care as long as I don't say the "F" word, really. I've said it a couple times and they didn't seem to care, but it's just a "strong" word and I don't like using it around the house (cause of my 'lil sister and brother)
Now, to frost. Yeah, that "F-YOU!" and flip of the finger deal can get ya in some trouble sometime

I once did it to this one guy (though he rightfully desearved it) while I was on my bike; I was crossing an intersection. I started going and so did he (though I started first) well, he basically ran me over, so I did what you do and he came back and punked me round in his car. Now, he was probably a senior or something and here I am, in 7th grade. What a pansy. Pickin' on a 7th grader, man :-/
I was young at the time and didn't really do much about it. Still p*sses me off to this day though. I hate for not doing anything back to him. Like spit in his face and ride down the street where a cop was waiting? heh.