No curse words at all?

So I remember about a year ago a Japanese man made a post here or in some other language subreddit. In it he has shown a video of a man yelling "you're an ass!" and ask for clarification, because he didn't understand why calling someone a body part would be offensive. That's more or less how I found out that Japanese has practically no taboo words per se, the way westerners do. However it has been brought to my attention that it doesn't mean Japanese people don't have any insults or offensive phrases you're not allowed to say in public unless. Can you guys give me any examples? What would Japanese people say when shit gets real?

by Aggravating_Size_180