First of all, the comment you replied to was clearly very sarcastic. If you hadn't been around Bernie and Sir C for so long, I'm sure it would've been obvious to you. 'Blacks with boomboxes' was supposed to convey to the reader the image of an out-of-touch, bitter bigot.
Second of all, I think this madman is essentially right: https://www.youtube.com/results?sear...k+racist+jokes