The Friends actress -- who portrayed Rachel Green on the beloved sitcom -- joined her Office Christmas Partyco-star, Jason Bateman, at a junket in promotion of their upcoming holiday comedy on Sunday, and Aniston had nothing but love and praise for Bayer.
"She's the sweetest," she said of the longtime SNL cast member, who also stars in Office Christmas Party. "This is something she's been doing since, you know, she grew up on Friends."
"Ugh, it's so sad when you say that!" Aniston added with a laugh. "But yeah, this was something she's been doing since her stand-up days. We had fun!"
ET also spoke with Bayer, who said it was "a dream" to get to do her impression of Aniston's Friends character with the actress herself.
"She had been very kind about the impression when we were shooting this movie," the 35-year-old comedian recounted. "She had seen me do it, but I had never done it in front of her until yesterday and she was a dream about it and she was just the best."
Bayer's SNL and Office Christmas Partyco-star, Kate McKinnon, praised Bayer's "nuanced" interpretation of Rachel Green as "the best impression I've seen."
"It sounds exactly like her but it's also just a funny character and take in its own right," McKinnon shared. "It's incredible."
"He is the life of the party," she gushed. "People are very bummed when he's not there, which makes me feel great."
This year marks their second Christmas as a married couple, and the actress said she is excited to spend the holiday together, after Theroux, 45, surprised her by coming home for the couple’s annual Thanksgiving dinner.
"He's been gone for so much of the year, it'll be nice to actually [be together]," she said. "He came back for Thanksgiving, so we're excited just to have another holiday."
Aniston, Bateman, Bayer and McKinnon star -- alongside Olivia Munn, T.J. Miller, Courtney B. Vance, Jillian Bell, Rob Corddry and Randall Park -- in Office Christmas Party, which hits theaters Dec. 9.