Armie Hammer's on-set debauchery was no laughing matter for a few of his Mirror, Mirror costars.

"Pranking was a big deal on set. Luckily I was never really the victim of many pranks," Lily Collins, 22, said during a NYLON magazine and Coach dinner party at Scarpetta Beverly Hills Tuesday. "I know that Armie put a fish in one of the dwarves' trailers and everyone forgot about it. That was probably not such a great thing!"

"We had a lot of fun moments, though. A lot of laughs," Collins told NYLON TV. "The whole time, we had such a blast."

Playing a fairytale princess like Snow White was a dream come true for Collins, who shared the screen with Julia Roberts, 44.

"I loved everything about the color of the story, the different characters," said Collins, who "also loved Princess Jasmine" growing up. "She was always one of my favorites."

Mirror, Mirror hits theaters March 30. Collins' NYLON cover is on stands now.