"I should've watched all 10 seasons because when I did the reunion and was asked questions, I was like, 'I don't remember being there,'" she said.
"Yeah. I don't remember filming so many episodes."
The cast reunited on the set of Friends last year to look back at the series that turned them into household names. Cox was joined by Jennifer Aniston, 53, Lisa Kudrow, 58, Matthew Perry, 52, Matt LeBlanc, 54, and David Schwimmer, 55, to share their memories of the experience.
"I see it on TV sometimes and I stop and go, 'Oh my God, I don't remember this at all,'" Cox added. "But it's so funny."
She admitted she has a "bad memory" and can't remember many of her own life events apart from shooting the series.
"It's really basic," she said.
"I don't remember any trauma in my childhood, but I have, like, three memories. I don't know. I don't know why."
The star confessed she was disappointed by her lack of memories.
"I'm kinda bummed that we didn't spend more time taking pictures. Because I don't have a lot to look back at," she said.
But one particular memory has stuck with her for years. The director of Friends James Burrows took the cast on a trip to Las Vegas before the show first aired in 1994.
"He gave us all $500. And he said, 'I want you to take care, like, really take notice of this moment because it will be the last time that all six of you together can walk through a casino,'" she said. "And we were like, 'Really?' And it was true. We never could never do that (again)."
"I mean, I don't wanna sound like, 'Look at us.' We're not, you know, the Beatles. But people feel like they know you," she continued. "If we were all to walk down the street, six of us, it would be, I think it would be really interesting to people."
Cox admitted some episodes are hard for her to watch. Some episodes were sped up to fit in an extra ad, which meant her voice sounded like "a mouse" or "Tinker Bell".
"Oh my God! I hate my voice so much."
Cox also said that she feels "lucky" that people still love the series as much as they do.