Hemsworth and Harrelson worked on the Hunger Games franchise and, most recently, in the western The Duel.
On the set of The Duel, which was shot in "middle of nowhere" Mississippi, Hemsworth and Harrelson occupied their free time by taking trips on Harrelson's converted school bus which he calls "The Mothership."
"It's painted with all like naked hippies and animals and flowers and rainbows and fun," Hemsworth said.
Though he was vague about what exactly goes on on the bus, it didn't take long for Conan and co-host Andy Richter to figure it out.
"You know... hanging out," Hemsworth said with a laugh. "Hanging out doing Woody Harrelson hobbies."
Richter mentioned that he has also seen "The Mothership" and that everything was made of hemp.
"Yeah, I guess we can figure out what you guys did," Richter said as Hemsworth laughed.