Scratch will remove a project with a single four-letter word. I think we won't be that fussy. By popular demand, we are now banning swear words on Snap!. As a general rule we've said we're aiming at PG-13.
Bullying of individuals is a super violation which is likely to get the poster banned. This includes the posting of revenge-PG-13-semi-porn.
Something that has occasionally been a big problem for Scratch is fake suicide notes in an effort to be funny. It's a problem because we have to take a suicide threat seriously, which can cause a lot of trouble in real life. It's not funny; don't do it.
We need to be sensitive to upsetting people with racial, ethnic, gender, etc. slurs. My personal opinion is that you should be allowed -- be encouraged! -- to read Huckleberry Finn even though it contains That Word. But I don't think we're in a position to fight that battle, so a slur in the speech of a fictional character is likely to become unpublished. A case in which a character (or the author in their own voice) says "Yesterday someone called me a ____" as the beginning of a conversation about calling people names might be okay, better than okay I think, even if what's in the blank is That Word.
Having said all that, this is just me talking, and what's in the ToS is really just me, too; none of my colleagues in this enterprise have expressed an opinion in the abstract, as in this conversation, but if a dubious case actually comes up, they may turn out to have strong opinions, so it's best if you don't try to be a ToS lawyer, and don't try to live on the edge just to see how far you can push us.