Why Lisa Kudrow's son called Jennifer Aniston 'mommy' on 'Friends' set?

Jennifer Aniston opened up about the sweet bond she shared with Lisa Kudrow's son during Friends days.

​During Variety's Actors on Actors series released this week, the Morning Show star reunited with her longtime pal and co-star Lisa and revealed that her son, Julian, now 28, used to call her "mommy" on the set of their hit sitcom.

​Lisa and Jennifer talked about how Lisa's show The Comeback, which also stars Julian, was shot on the same stage where Friends was also filmed.

​Jennifer looked back, saying, "It's like he grew up hearing laughter all the time."

​In response, Lisa said, "I know. Can you imagine? Just the amount of joy. Because it was the most fun."

​Jennifer then expressed her admiration for Julian, saying, "He is today one of the most joyful human beings that I get to spend time with. Like, I love him."

​"I would choose him as a person I would like to spend time with as a friend, not just because he's your son."

​Lisa then recalled the sweet memory, noting, "When he could first speak, he'd look at the TV, point to Jennifer and say, 'Mommy!' So he had a connection to you."

​Jennifer chimed in, "That was weird. He knew, somehow, that that would make me feel good."

​Elsewhere during the conversation, Jennifer made a rare remark on the cameo of her ex husband on the set of Friends for Thanksgiving special episodes.

​Jennifer asked Lisa, "Did you like the Thanksgiving episodes? Those were fun."

​Lisa replied, "Yes. Those were great, the Thanksgiving episodes. When Brad was on, that was hilarious' with Jennifer saying, 'I know. How funny. The movie stars that came on Friends. Brad, Bruce Willis, Julia Roberts. Isabella Rossellini."

​"We had so many - Sean Penn. They were always nervous. Remember? I always found it fascinating how nervous they were," Jennifer added.