It all started with Letterman's less-than-awesome introduction of the pop star before her 1994 appearance: "Our first guest tonight is one of the biggest stars in the world. In the past 10 years, she has sold over 80 million albums, starred in countless films and slept with some of the biggest names in the entertainment industry." Burn! Even faithful sidekick Paul Shaffer couldn't help but object. "She's your guest!" he bellowed from off-camera. To which Letterman responded, "It's right there on her bio, for heaven's sake."
Needless to say, Madonna was less than amused, and decided to enact revenge by dropping the F-bomb a record 14 times and making endless sexual innuendos (including comparing a microphone to a certain part of the anatomy, ahem). At one point, Letterman exclaimed, "This, of course, won't see the light of day." It did (of course), and became one of the highest-rated shows that year. But that didn't stop Letterman from making another joke at Madonna's expense the following evening: "You can tune in safely — she's not on tonight!"