I couldn't find the one I was looking for. It might have been Joe Pizcopo, but I thought it was Steve Martin and Dan Aykroyd. Back then we didn't have VCRs and YouTube so we had to remember it as we saw it, and I'm pretty certain that these were part of the lyrics:

" I'm white, I'm extremely white. I walk with my butt extremely tight.
I'm a white guy, and I take no crap - when I deliver my white rap! "

~ Saturday Night Live c.1984-ish I think.

Before anyone gives me shit about being in a White school, I'll have you know that Windsor, Ontario is very multicultural, and all of loved comedy regardless without all the baggage of today, and within my tighter circle of friends 1 was Black and my best friend from grade 7 (1983) past university was born in India. Obviously there were many more of different origins that I was friends with outside that circle. My friends of colour expressed that some people treated them differently when I said racism was over even though I did see it on very rare occasions when brainless dicks were being bullies, but otherwise when with them I didn't see it much in the world at large.