"What's so funny about Sly is that he isn't intimidating, despite who he is," the 21-year-old Cook tells TV Guide Online. "You have this preconceived notion of him as a big, tough guy, but he speaks four languages and he likes to water color. Also, he's very funny."
For instance, Cook -- currently in Canada, filming the live-action Josie and the Pussycats -- recalls a scene in Get Carter when Stallone's wacky side surfaced. "We have a scene in a hotel room, and he got it into his head that it would be really cute to dump me off the bed. So, without warning me, he picked up one side of the mattress and practically threw me on the floor. What's really funny is, the director decided to use that take."
Despite the fun and games, Cook concedes that she learned a lot about acting from her Oscar-winning co-star. "He has very high expectations," she says. "He raises the bar; he definitely improved my game. You have to be ready because he won't tolerate anything less."
Cook also concedes she was more than happy to take a break from the generic teen roles that typically come her way. "Acting is about experiencing things you haven't in real life," she says. "Otherwise, you'd just be doing a lot of depressing home movies.
"I get offered angst-y teen parts all the time," she adds. "But the girl I play in this film has a reason for it. She's genuinely traumatized, not just angry for the sake of being angry."