Lawrence, 24, joined X-Men: Apocalypse costar Munn and an impressive celebrity cast to perform the script from the popular Coen Brothers's film during the Just for Laughs Festival in Montreal, Canada.
The actress, who was reading for Jeffrey Lebowski's daughter Maude (a part originally played by fellow Oscar-winner Julianne Moore), had a script mix-up with Munn, who was playing Bunny, Maude's stepmother, according to Mashable.
When Munn read Lawrence's opening line, the entire cast was confused.
"It was highlighted, motherf-----s," Munn said before switching script pages with the Silver Linings Playbook star.
"We've been waiting three hours to get to my part and it's all falling to s---," Lawrence responded, reported Mashable.
Michael Fassbender, who read for the film's star, "The Dude," got very into his role as the laid-back burnout who gets accidentally embroiled in the Los Angeles underworld.
Fassbender donned Jeff Bridges' character's signature bathrobe and boxers, smoked cigarettes and drank a cocktail during the reading.
R Chiang / Splash News
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Mike Judge (The Stranger), Martin Starr (Jesus), Dennis Quaid (Big Lebowski), Mae Whitman (Donny and one of the Nihilists), and T.J. Miller (Brandt) rounded out the cast.
The special performance was organized by director Jason Reitman and drew an audience of 1,300, according to Variety. The director regularly coordinates star-studded readings of popular screenplays.