(informal) Something very funny; a comedy session or period of great amusement.
1995, Paul Auster, Mr. VertigoOh, I had a jolly time in South Dakota, all right, a regular laughathon of nonstop fun and entertainment
2000, Mike Douglas, Thomas Kelly, Michael Heaton, I'll Be Right Back: Memories of TV's Greatest Talk ShowThey were already into that raucous rhythm that made their show a TV landmark. Nonstop jokes, topping each other, full speed ahead, no holds barred laughathon.
2002, Terrence D. Haynes, Desert Norm: A Journal/Novel About the Gulf War (page 169)It was a laughathon at Headquarters.
2004, Carrie Asai, The Book of the Shadow (page 36)What if they were having a big laughathon over Heaven and her stupid crush?
