For the game, Lawrence, Fallon and special guest John Oliver sat around a moodily lit table with two envelopes in front of each of them -- one containing a true confession, and the other containing a lie. Each player had to open an envelope at random and do their best to sell the story, regardless of its veracity.
The 25-year-old Oscar winner was up first, and her story sounded almost impossible: "I once took an Ambien before filming a scene in The Hunger Games."
"We're you sleeping in the scene?" Fallon joked, trying to get her to reveal her hand to no avail. In fact, Lawrence claims she took the strong sleeping aid before shooting a scene in which she had to dance.
As for her reason for dropping the sedative? "I thought it was something else," Lawrence said, laughing.