Jerry O'Connell Can't Stop His Baby Girls from Giggling

By Lisa Ingrassia

08/25/2009 at 07:45 AM EDT

On movie sets and on stage, Jerry O'Connell may have limits to what he'll do for a laugh from his audience. But at home, he finds himself doing just about anything to get giggles out of the fraternal twin girls he and wife Rebecca Romijn welcomed last December.

Luckily, they're a generous audience. "I think of myself as a funny guy but nobody thinks I'm funnier than my daughters [Charlie and Dolly]," O'Connell, 35, tells PEOPLE. "We have three dogs. If I act like one of the dogs with the dogs, they go crazy. It's like we're talking Richard Pryor in his heyday."

O'Connell, who has been taking care of the girls while his wife films her ABC show Eastwick, says his 8-month-old twins even laugh when he's trying to discipline them.

"Whenever I try to scold them, if I'm feeding them and they put their hands in the food bowl, or when they're pulling each other's hair, they think it’s the funniest thing in the world," he says. "They don't know how cool they're being. They're like Dwayne 'The Rock' Johnson."

The joy in the Romijn-O'Connell household is a two-way street. "There's no better feeling than making your little girls laugh," he says, but showing them off comes in close second. "One of my favorite things is putting them in their carriage, walking them around, and having people stop me and saying, 'Tell me about your girls.' There's something fun about it. It's like having a new car except it's two lives. I'm proud."

As much as he enjoys fatherhood, the actor says he thinks his family has reached full capacity. "My wife said, 'The factory is closed,' " he deadpanned. "That's not a lie. The factory is closed! You can't make anything else."