Reese Witherspoon recalls being ‘terrified’ on ‘Friends’ set and what Jennifer Aniston told her

Reese Witherspoon can still recite her "Friends" dialogue from more than two decades ago.

The Oscar winner, who played Rachel Green's spoiled sister Jill on two episodes of the hit NBC sitcom, reminisced about sharing the screen with her "Morning Show" co-star Jennifer Aniston during a recent visit to “Late Night with Seth Meyers."

"I was (Aniston's) younger sister on 'Friends,'" said Witherspoon as Meyers held up a throwback photo of the duo on the show's set.

"Yes, and the funny storyline was I started dating Ross (David Schwimmer) because she and Ross were on a break," she continued.

“And (Rachel) gets really jealous and she’s like, ‘You can’t date Ross.’ And I was like, ‘I can’t? The only thing I can’t have is dairy,’” Witherspoon said.

“I mean, I still remember the line,” she added.

The actor, who stars opposite Ashton Kutcher in the upcoming Netflix rom-com “Your Place or Mine,” recalled how scared she was when she first walked onto the "Friends" set.

"So, I was terrified," she said. "I was out of my body. I was — my body was there and then my head and my brain were somewhere else."

"I just had a baby," continued the actor, who welcomed daughter Ava in September 1999. "So that's how I know it was 23 years ago because now my baby is 23."

The "Legally Blonde" star told Meyers she was thrilled when she walked into the show's famous coffeehouse.

"Walking into Central Perk ... and sitting on the couch, I was like, 'Oh, my God, I can't believe this is happening. Oh, my God, there's Joey. Oh, my God,'" she remembered thinking.

Then, Matt LeBlanc, who played Joey, used one of his character's famous lines on Jill. "And then wait! Joey said to me, 'How you doin'?'" said Witherspoon, laughing.

Witherspoon noted that her TV sister helped calm her nerves.

"I was terrified but Aniston was so sweet to me," she recalled. "She was like, 'They don't care if you mess up. They actually like it better when you mess up.'"

In October 2019, Witherspoon and Aniston delighted “Friends” fans when they re-created their famous “The only thing I can’t have is dairy” scene during an interview with "Access Hollywood."

As hilarious as Witherspoon was as bratty Jill, she wasn’t the only Hollywood star to play a Green sister. Christina Applegate also guest-starred on the show as Rachel’s other self-absorbed sister, Amy.

In June 2019, the “Dead to Me” star opened up to TODAY.com about how excited she was to appear on the sitcom, describing Amy as a “selfish” character who had “no filter.”

Applegate’s favorite memory? When Rachel and Amy’s sibling tiff turned physical, which allowed Applegate and Aniston to show off their impressive slapstick comedy skills.

“That was where the audience really lost it,” recalled Applegate of the over-the-top fight. “It was just ridiculous and it was so much fun to do.”

This article was originally published on TODAY.com