The arrived/left/disconnected thing, as Red said, can be disconnected by going to the Options screen (located just an ESC key press away, if you didn't know), and scrolling down. Click on "Arrival Chat Name Type", and select the option, "Don't Show".
FH is an all ages game, so it's honestly not the game for you if you're miffed about cursing and a few dirty jokes, but some of the worst behavior could definitely use some work.
I feel like a creep for stalking around the Opinions thread and giving advice, but here I go again;
If someone sexually harasses you in a way that makes you feel uncomfortable, ignoring them may only be the second best option. Your best bet could be responding in a straight forward, almost aggressive way.
My mother made me take a "Woman's Defense" class once. Because I take public transportation, and she believes I'm going to get raped on a bus full of people.
The class taught us that when being assaulted by a sexual harasser, to not respond passive-aggressively, but with aggression. You need to establish that what they're going is NOT okay, and is making you uncomfortable and hurting you. And don't dish it to them gently either. You have to seem generally upset, like you resent them.
If being a teenager has taught anyone anything, it's that people will change their behavior when they start to feel like they're being hated for something.
Aha, we can use peer pressure to eliminate the sexual harassment? XD;