The 49-year-old actress has revealed that her little boy is George's biggest fan and loves to spend "man time" with George and his friend Rande Gerber, the husband of Cindy Crawford.
"My son thinks he's the coolest dude," Sandra revealed at a Toronto Film Festival press conference for Gravity, her new film with George.
"If there's a choice between me, and George and Alfonso (Cuaron, the film's director), my son will leave me to be with George and these guys. He's a boy's boy, so he has to go talk to the men."
The Oscar winner — who adopted Louis in 2010, within months of her high-profile spilt from husband Jesse James — said her little boy actively seeks out time with her Gravity co-star.
"The cute little anecdote is that he went to me and said, 'Where's George and Rande?" she revealed. "I said, 'I don't know'. And he said, 'I need them!'
"So we went and found them, and they had man time. And I sort of stood off to the side and waited for them to finish," she said with a laugh. "Then I was allowed to take him back."
Despite being friends for a number of years, Sandra and George hadn't worked together before starring in their new space drama.
"George and I have known each other for over 20 years. We've known each other since we got out of college and we have the same group of friends," Sandra told reporters at the press conference.
"We knew each other since we had no work," she quipped.
Despite their subsequent fame and success, she said that George, 52, has remained the same person — except for one thing.
"He has better hair now!" she joked. "There's less of it, which I appreciate. The big curls were cute, but you know… Really he's taken his blessed life and done amazing things with it."
She added, "George is a good man, and I'm really proud to have known his for this time and the human being that he's become."