Fallon debuted the new game in honor of former Tonight Show host Johnny Carson's famous game of Twister with actress Eva Gabor, which went down 50 years ago.
The Café Society star tied her coat around her waist and got down to business on the stage floor as the two contorted their bodies while also downing some massive, Jell-O shots.
"These are gargantuan shots," Stewart laughed, as she struggled to slurp down the colorful shots.
"You don't have a premiere or anything tonight, do you?" Fallon joked.
As Fallon's announcer and right-hand man, Steve Higgins, called out foot and hand placements, it became increasingly apparent that the 26-year-old actress was a bit more nimble and limber than the 41-year-old host.
Finally, after Stewart strategically forced Fallon into a difficult pose, the final move pushed Fallon off balance and sent him sprawling to the floor. Stewart was her usual shy self as she bashfully basked in applause.