From left: George Clooney, and Sandra Bullock with son Louis
Getty; X17 Online
10/02/2013 AT 12:30 PM EDT
When it comes to bonding with Sandra Bullock
's 3-year-old son, Louis, George Clooney
does it with a game of hoops.
"Louis and I played basketball together," Clooney, 52, told PEOPLE at Tuesday's New York premiere of the space drama Gravity
. "There was [director] Alfonso [Cuarón] and Rande Gerber, and Louis would gravitate towards me
and the guys and hang with us."
The leading man added, kiddingly: "It was fun, but I wish Sandy would stop telling the story, because it's totally ruining my reputation!"
Although Clooney isn't called "Uncle George" or any other nicknames, Clooney says he enjoys spending time with the boy and his good pal Bullock, 49.
"Sandy is the best. We've been really close friends for a long, long time," he said. "She likes to say 20 years, but it's been a little longer than that. So just the idea that I got to work with her was a blast."
And how did the two superstars become friends?
"She was dating one of my best friends, a dear friend of mine for a long time," the Oscar winner explained. "I got to know her long before any of us had succeeded. When she hit it big in the Sylvester Stallone movie [Demolition Man
] – that was her big break in the film world, and we were all very excited for her."
Today, Clooney remains Bullock's biggest booster, and applauds her for taking on a highly physical and emotional demanding role in Gravity
"She's an incredible actress and gives a powerful performance," he said. "I really had a much easier time than Sandy did. She worked twice as long as I did. She should be very proud."