Oh ffs not this free speech dance again. Yes you can’t make threats against people. That’s not protected speech that’s just a threat. In that case none of the words are against the law to use, but it’s how you combined them and directed them at someone that becomes illegal. You also can’t yell fire in a crowded building as that is considered inciting a riot or whatever. Again the words themselves are not against the law it’s when and how they are used that is an issue.