The stars appear alongside each other in new movie "Money Monster" after having previously worked together on "Ocean's Eleven" and "Ocean's Twelve", reported People magazine.
"We met on Ocean's. We had actually never met before. People just thought we had," he said.
From there, their lives became intertwined, with Roberts staying at the 55-year-old's home in Lake Como, Italy when she was pregnant with her twins, Hazel and Phinnaeus, now 11.
"She brought all those monsters back to the house when they were actual human beings and we've had a blast with them," George added, also referring to Julia's eight-year-old son Henry.
"Danny and I are great friends and love each other," he said.
"What's fun is it's really like a family. It makes it easy. It's really fun to go, 'Hey, let's do this movie together'.