I'm sure you've all seen Joaquin Phoenix's burly appearance on Letterman from a few nights ago. God bless the American public, for in their innocence they don't realize that Joaquin was pulling an elaborate Borat-like joke for a movie filmed by his brother-in-law Casey Affleck; it's much easier to talk about how "messed up" the guy is, how he'll probably OD soon, etc.
Joaquin Phoenix on Letterman wasn't a TV melt-down. It was funny because he was Quantum Weird AND allowed Dave to make fun of him. Great performances by both of them.
If you want to see a real TV chat show melt down, try this wondrous clip: two great Americans, who depending on the day were good friends or great enemies, going at it on the show of another great American. Mailer comes off like the most pompous man alive, Vidal is his impish self, but the best lines of the night belong to Cavett. Watch and enjoy.