We all know now that Feb. 11 was a blur for Joaquin Phoenix, and Feb. 12 turned out to be a blurry cold/flu vision for me, but who will look at this Friday the 13th and find it blurry? Spoiler alert: Probably you. That said, the Phoenix interview on The Late Show with David Letterman got me thinking about Letterman's many great and infamous moments over the years. There are a few people who look upon their Letterman spots as times to shine, whether it be for good (Bill Murray, Martin Short, Bruce Willis) or those who use him for their own evil self-purposes (Bill O'Reilly, Howard Stern, Paris Hilton). And then there are those who, well, just sort of take over the show, whether they meant to or not. This blog post is devoted to those celebs who took Letterman by surprise before Joaquin Phoenix.

The nine greatest moments in David Letterman interviews, after the jump.

1) Farah Fawcett. Let's start with Fawcett, because Letterman name-checked her near the end of his chat with Phoenix. She appeared on the show in 1997 to promote her Playboy pictorial and a new DVD that also showed how well she had aged. Only problem was, she couldn't make any sense out of anything.

2) Andy Kaufman. When people talk about hoaxes, this is the first thing that comes to mind, as Kaufman brought his "feud" with professional wrestler Jerry Lawler into network late-night TV. This is re-created as part of the Kaufman biopic, Man on the Moon. It really seems as though Dave has no idea what's going on here.

3) Madonna. I remember hearing about this one for more than a 24-hour blog cycle, as people talked about all of the profanity Madonna uttered, and how awkward it all got for Dave. Although watching it again now, it almost seems as though he started it with his intro. Don't you think?

4) Courtney Love. Oh, how she tried to duplicate the funny surprise that Drew Barrymore presented for Letterman's birthday, except everything goes terribly wrong. She wants to blame it all on the FCC, but really, the blame is on her.

5) Harvey Pekar. This was from his final appearance. Letterman banned him after this final conflict.

6) Cher. It's 1986, and she explains she has not been on the program because she hates Letterman. No, wait. She likes him, but merely thinks he is an a-hole. Talk about awkward. It does get better, though.

7) Crispin Glover. This is the other totally weird performance that Letterman could not figure out at the time, and he cited Glover first (and then Cher) as his most frequently asked guest during his NBC era.

8) Richard Simmons. This is from what could be his final appearance, as Dave and the crew apparently decided they had had enough of his antics and wanted to punk him once and for all.

9) Michael Richards. The only thing weirder than Michael Richards freaking out at a heckler in Los Angeles was his haphazard apology to Letterman, via satellite, with Jerry Seinfeld on the set. Who said this was a good idea, again?