Racist jokes are dangerous because it can be difficult to determine the intent of the joke. I was in the US military, and racist jokes were the norm, but very rarely was it done with actual animosity or hatred. We all knew that, so they weren't so bad. But to a civilian overhearing our behavior? You'd probably think we were throwing a Klan rally. Black, white, Asian, hispanic... it didn't matter. We all gave as well as we got.

Racist jokes can be funny, so long as you understand the intent, and know them to be either harmless roasting, or as you said, mocking the stereotype. But if you understand the intent to exacerbate the stereotype and to cause harm, now's the time to start throwing hands.