Michael Jackson

In one episode Homer gets admitted to a mental Asylum for wearing a pink shirt to work. Whilst in the asylum he meets a Fat White guy who proffeses to be "the small black guy" (Quote Bart) Michael Jackson. Although at the time is says Michael Jackson did not do the voice for this character, it was later revealed that he had but he did not want any credit for it.

The real Michael Jackson is also a huge fan of the Simpsons and works with them especially when they create music etc.