So he called this a joke? Where's the joke? Which part are you supposed to laugh at? This isn't humor, this is just spewing ugly hate at a TV screen.
If you have a problem with it, don't dismiss it anymore. People say racist things like this when they think they can get away with it. Don't let him justify it with, "Oh, I'm not racist because I have a lot of black friends and it was just a joke anyway." That's a bullshit excuse and it doesn't give him carte blanche to say horrible things.
Maybe you can find a documentary on Netflix that demonstrates how not to be a racist piece of shit. Watch it together. Make it a date night. Serve fried chicken and watermelon. [URL="http://www.youtube.com/watch?v=obKLdou0LH0"]Ba-dum chh![/URL] Now there's a joke!