There was an amazing attempt to blackmail David Letterman for $2 million. The allegation was that David Letterman had been having sex with some of his female staffers. In order to keep this secret the blackmailer demanded $2 million.

Letterman played along with this, having informed the authorities, and handed over a fake cheque for the amount. It was later revealed that Robert Halderman was in custody over the issue. What trule shocked was the way that Letterman then used a segment of the Late Show to point out that the allegations were in fact true.

Here's the full video of David Letterman explaining the exotortion attempt and admitting to the allegations.

There's a lot more about the David Letterman extortion at that link.

Perhaps the most bizarre piece of this whole extortion or blackmail
attempt is, well, so what? Showbiz is not exactly known as one of those
areas of life where people, whether men or women, keep it zipped up is
it? All those jokes about the casting couch have more than a grain of
truth to them. Seriously, an extortion attempt over rich man, rich
famous man in showbiz, has sex with women who are not his wife?

Is
this really even news, let alone the necessary scandal to underpin a
successful blackmail attempt? Actually, clearly not, as Letterman has
announced the deeds rather than making the payment, rather neatly
making the point that the secret just ain't worth two million dollars.