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At least it wasn’t nightlock berries. Jennifer Lawrence visited Jimmy Fallon on "The Tonight Show" on Monday for a revealing game of "True Confessions," and the "X-Men: Apocalypse" star shared a little-known behind-the-scenes tidbit from the production of The Hunger Games.

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.

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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.

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After 60 seconds were up, it was time for Fallon and Oliver to take a stab at whether or not she was telling the truth.

"This could go either way for me," Fallon said.

"It's plausible. It's reckless. I kind of like it," Oliver replied. "If it's not true, I'm going to be very sad."

As it turns out, Lawrence was telling the truth. Unfortunately, she didn't elaborate on which scene from the action adventure featured her on the brink of unconsciousness.

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The Oscar winner did, however, have another embarrassing moment when Fallon pointed out something on her face.

"Was it a booger?" she asked, wiping it away. "I totally felt it!" Oh, J.Law.