Bradley Cooper quickly learned just how much she was going to do whatever she wanted -- and that before he even knew who she was.
It all went down at a party at Chastain's place, where both Cooper and her grandmother were guests. Well, grandma took it upon herself to make herself quite at home.
"In the middle of the party, she just walked over to Bradley and just sat on his lap," Chastain shared, making sure to emphasize that Cooper had absolutely no idea who this woman was at this point in the evening.
"He looked horrified, actually," she recalled. "He had never met her, he had no idea who she was."
"I saw it kind of happening in slow motion where I was like, ‘No!’" Chastain said of the shocking moment. She quickly sprang into action, shouting out to him, "It’s my grandma! It’s my grandma!"
"Then he was like, ‘Okay, okay. Hi, Grandma," Chastain laughed. So all's well that ends well -- especially if Grandma gets to end up in Bradley Cooper's lap.
While that was all playful fun with an incredibly handsome man, Chastain said that she actually has been trying to get her grandmother back into the dating scene (though maybe not with Cooper).
"I've been trying to get her dates for a long time; a boyfriend," said Chastain, revealing that she's made this her pet project for nearly two decades now. She even got her grandma and Al Pacino in a picture together after working with the actor on a film, putting it on her grandmother's nightstand.
Honestly, though, if grandma has reached the sitting-on-strangers-laps stage of her life, she may not need any help in this department. It sounds like she has absolutely no problem seeing what she wants and laying claim to it!