What: Jon Stewart’s October 15, 2004 appearance on CNN’s debate series Crossfire:

Why: It’s hard to imagine CNN as a news network, but it did once have a role of bringing news to America. (Yes, kids, MTV used to show videos too.) Those days are long gone, and what is left is a series of so-called “debate shows,” the king of which was Crossfire. If you wanted bluster from the left and bloviation from the right, you came to Crossfire. But in 2004, in the heart of an election, Jon Stewart came on the show not to talk about comedy or politicians or his new book, but instead with a message for the hosts: “Stop… Stop… Stop hurting America.” The hosts were the liberal Paul Begala and the goofily bowtied conservative Tucker Carlson, to whom Stewart said, “You’re partisan, whaddaya call it, hacks.” Stewart dismissed the notion of Crossfire being a debate show, labeling it mere “theater.” By the end of the show, Carlson was reduced to calling Stewart “John Kerry’s butt-boy,” which must have made Carlson’s bosses at CNN proud.

Impact: Seen any good episodes of Crossfire lately? No? Maybe it’s because within a few months of Stewart’s scorched-earth appearance, CNN cancelled the show after 23 years on the air. Stewart took a sledgehammer to the network’s integrity, and it hasn’t recovered. I can’t look at the sports-bar set of The Situation Room without wondering how anyone watches CNN with a straight face. Meanwhile, the subgenre of the on-air beatdown has fostered a number of sterling examples, the most recent being MSNBC’s Chris Matthews’ evisceration of radio host Kevin James over Barack Obama’s so-called “appeasement.”

Personal Connection: I used to watch CNN all the time, but now the only news I watch now is on BBC America. CNN’s meltdown as a credible news source, along with the retirements and deaths of the anchors I watched, caused me to return to my primary source of news in my youth: the newspaper. Now, I read several newspapers every day … online.

Other Contenders: Richard Hammond descends a showgirl-bedecked jetway to return to the UK car show Top Gear months after a brain-damaging 288-mph dragster crash; Johnny Carson genteelly debunks “psychic” Uri Geller; Sarah Silverman has a surprise for her boyfriend Jimmy Kimmel involving her friend Matt Damon; Rosie Perez describes her new truck to David Letterman; Tonight Show host Conan O’Brien flashes a copy of my game Yetisburg.