if you're using racism as your insult aren't you kind of establishing yourself to already be scum? its like that kid that says "kill yourself" to everyone. You eventually learn that the kid has social issues and try to ignore him as much as possible.
Theres not even a justification for racism outside a joke. Sure, you can make a joke about how I have no father or how I hate education and i'll actually laugh irl because its a joke. But people who say stuff like "shut up monday go back to your tree rope" are just edgy through and through. Even if you do something as light as just say the word monday in regular conversation you're already establishing yourself as a cunt.