Bill Hicks, my favourite stand-up comedian/philosopher/"Noam Chomsky with cock jokes" ((His own term.)) went on the David Letterman show a few of times, but on his last occasion there, he was censored right off it. Letterman and his people had said OK'ed Bill's jokes before and after he want on, but because of his joking about pro-lifers they completely censored his appearence.

To say Bill was against this would be the understatement of the year; he even wrote a 39-page letter to John Lahr ((As stated here.)) of The New Yorker explaining his frustration, sadness and anger.

Here's a video where Bill explains how he feels about censorship, and he does jump straight to the Letterman affair:

Now, more than 15 years after the show was taped, Letterman apologises to Bill's mother (Mary Hicks) on the show, and shows the entire appearence. It's really beautiful and heart-warming, I laud Letterman for apologising, and I miss Bill more than ever. Here is his mother's appearence and of course Bill's previously censored gig at the end:

Less than a year later, Bill Hicks died from pancreatic cancer, merely 32 years old.