Are there topics you can't/shouldn't joke about? Why or why not?

I don't think there's topics you can't joke about but I do think there are limitations. There's people and places you shouldn't make those jokes in or towards. Humour is abstract, some use it as a copying mechanism, others use it as a tool of communication. You can't use it the same way in every interaction. Reading the room and being tactful is equally as important. That's why there's some comedians out there that make dark jokes that I can get with and others that joke about the same things that I don't find funny. For example, joking about racism. I've found jokes funny that's delivered in a sardonic tone as to mock racists as opposed to actually being racist. Then you have people that regurgitate outdated, predictable stereotypes and call it a joke. They're not the same. The topic in itself isn't off bounds but if you're gonna joke about it, the key is making sure the targets of the joke are laughing with you