I don't know why this has to be said
There are some things you shouldn't joke about or use as insults. It doesn't matter if you think it's funny or not, or if it's attacking someone or not, some things are just not okay, for example:
-Suicide: I went through a thread where someone posted how an enemy jokes about a famous streamers suicidal intentions. Most of the thread was fine, but some people dismissed the joke since it wasn't "go kill yourself" and just "dark humor".
It doesn't matter if it's dark humor or not, when you joke about suicide, you're making someone's feelings into a joke. You're telling them that it doesn't matter and that they are a joke.
-Mental illness/disabilities: This one seems to stem from early Internet, where people think it's okay to call someone autistic and use it as an insult, sometimes calling them the r slur. I've seen it many times, and it's really disheartening, because you know what? Some people are autistic, and saying stuff like that is really messed up and inforces that being autistic is not okay.
-Sexual assault: This goes for everything. I don't see how people find it funny when joking about child sexual abuse when someone plays Annie. Or telling someone they're going to rape someone.
-Racism: Like, what year is it? What gives you the thought that it's okay to call someone the n slur? What makes you think it's okay to make racist comments about any race?
Sorry if this seems random, but I thought just saying "don't be a dick" wasn't specific enough, and people needed example of what not to do, because some people don't understand that "being a dick" doesn't specifically mean "insulting someone". You can add other things I missed and I'll probably add it in.