Let me ask a simple question: Can you tell the difference between what is a joke and what isn't? 

The answer is different depending on the person, I'm not saying that it's necessarily okay to make offensive jokes but it depends on if the joke being made is intentionally targeting a group in a negative manner or not. People are different in their opinions and views so it is literally impossible to gauge what is funny or what is offensive. 

It's all a matter of perspective.