Jessica Chastain's grandmother once sat on Bradley Cooper's lap at a party

Jessica Chastain has recalled how her grandmother once surprised Bradley Cooper by sitting on his lap at a party.

During an appearance on The Ellen DeGeneres Show on Wednesday, the Molly's Game actress detailed how her grandparent, Marilyn Herst, didn't hold back when it came to taking her chance to meet the A Star Is Born actor.

"A few years ago, I had a party at my house and Bradley Cooper was there. My grandmother is now at the age where she just really doesn't care, you know? She's just like, 'I'm just gonna do whatever I want.' So, in the middle of the party, she just walked over to Bradley and just sat on his lap," she sighed. "He looked horrified, actually. He had never met her. He didn't know who she was."

Sensing Bradley's confusion over the situation, Jessica immediately stepped in and promised the star he wasn't being attacked by a random guest.

"I saw it kinda happening in slow motion where I was like, 'No!' I just started going, 'It's my grandma! It's my grandma!' Then he was like, 'OK. Hi, Grandma,'" she laughed.

Elsewhere in the chat, Jessica shared that she has been trying to get Marilyn to go on dates for many years, and even set up an online dating profile for her.

"I've been trying to get her dates for a long time. I mean, it's been maybe 15 years, 20 years... I used to take pictures of her and put them on Match.com," she smiled. "I worked with Al Pacino - she was very excited about that. I took a picture of the two of them together and it was on her bedside table."