Why is Thanksgiving such a perfect setting for marathons? (The non-physical kind, of course.) Is it because the entire holiday weekend is dedicated to extended bouts of gluttony and shopping till one drops?

No matter the reason, this Thanksgiving not only brings the return of the MST3K Turkey Day marathon, but it also ushers in this year’s Never Not Funny Pardcast-A-Thon. Launching the day after Thanksgiving at noon PT, hosts Jimmy Pardo, Matt Belknap, and Pat Francis will live-stream 13 straight hours of auditory and visual comedy goodness in support of Smile Train. This year’s guests include Zach Galifianakis, Patton Oswalt, Andy Richter, Joel Stein, Scott Aukerman, Doug Benson, and radio legend Phil Hendrie.

Now in its fifth year, the Pardcast-A-Thon has grown from a nine-hour romp in 2009 to the current jumbo-sized run. To date, the Pardcast-A-Thon has raised over $300,000 for Smile Train, a charity that seeks to repair cleft lips and palettes in children all over the world. “I donated money to Smile Train just one Sunday after seeing it in the back of Parade magazine,” Pardo told EW. “I saw the picture of the child and it said for $250 and a 45-minute surgery, you can change a child’s life. My dumb little head understood that. I’ve donated money before to other great causes, but for $250, I’m really gonna understand what’s happening here.”

Pardo shared his experience with friend and collaborator Pat Francis, and Francis revealed he had also just donated to Smile Train. That’s where Pardcast-A-Thon was born. “For whatever reason, Smile Train responded to the idea that we were doing this for them, and it’s a comedy show, so they’re putting smiles on kids’ faces, and I’m a comic putting smiles on people’s face,” Pardo said. “It sounds a little cheesy, but everything really worked out and that became our charity of choice.”

It was initially an overnight project, which took a cue from one of Pardo’s idols. “I grew up loving the Jerry Lewis telethons,” said Pardo, who also serves as the warm-up comic on Conan. “As a kid, I liked the idea of being up at 3:30 in the morning and seeing what act was willing to come out at that hour. And seeing Jerry Lewis and his co-hosts being all groggy because it’s late, but they’re still there to entertain the audience and entertain the home viewer and raise money. That was another reason I wanted to do it overnight — let’s see what we’re like at 5 in the morning. But after doing that for three years, that kitsch factor kind of wore off.”

But just because the Pardcast-A-Thon is running during a more reasonable time frame this year doesn’t mean the team won’t hit a wall. “Every year there’s always a moment at the seven- or eight-hour mark where we hit a little lull and we get loopy,” Pardo said. “Then all of a sudden we see the other side, like, ‘Oh, we’re done in four hours!’ So all of a sudden everybody gets their energy back.”

Check out this year’s Pardcast-A-Thon (and donate to Smile Train) at Pardo’s website, or interact with the Pardcast-A-Thon at Laffster to bid on items donated by the guests. And do yourself a favor and check out Pardo’s podcast Never Not Funny, one of the sharpest and gut-bustingest shows on the Internet.