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"I've been able to meet a lot of people in this business … and it's so fascinating how many people are not what you think they would be and Jennifer Aniston is everything that you would ever hope that she would be," Munn, 36, shared. "She is, no pun intended, the friend you would want her to be."
"She's strong and she's smart, and she is a real champion for the other [actors] in the movie too," she continued. "Some people only look at their role and she's really down to help and figure out everybody's role."
However, off-screen, Munn and co-star Jason Bateman say they have a much better grasp on their party habits than their characters.
"I cut myself off usually around two drinks," Munn shared. "Just because it's actually more fun to remember what you did than to get blackout drunk."
"Although in this movie, I don't think any of the characters remember anything from the next day," she added. "This is a blackout drunk movie!"
As for Bateman, he reaches his cut-off limit before he's even had his first drink.
"I lost my fun chip about 15 years ago," Bateman, 47, joked. "Back in the day, my cut-off was right around sleep time, which was far too late, that's why I like the flat water now. When some of your vomit ends up on the person's jacket you're talking to, it's a [warning] flare."
ET caught up with Munn on the set of Office Christmas Party earlier this year, where she happily teased all of the film's wild insanity.
"People are giving themselves the excuse to hook up with the other coworkers, wear the most flashy outfits they have and to drink and debauchery is rampant," Munn explained. "This movie is every office Christmas party times 100." Check out the video below to hear more.