Ashton Kutcher isn't too worried about becoming a father for a second time as he "didn't break the first one".

The star and his actress wife Mila Kunis are currently expecting a brother or sister for their two-year-old daughter Wyatt. While Ashton jokes he was almost like a doula the ahead of the first birth, reading books and studying, he has relaxed his preparation this time round.

"I was reading every book, I was ready, had a catcher's mitten on ready," he told talk show host Jimmy Fallon. "This one, I haven't done anything. I'm like, well we already didn't break the first one. They're really durable, that's what you realize, they don't break very easily. You have to kind of try to break them."

The couple recently celebrated Wyatt's second birthday by throwing a party with the theme of British kids' show Peppa Pig. It seems the cartoon characters' accents have rubbed off on the family, with Ashton explaining he and his little one walk around the house copying the pig family's favorite phrases, such as "muddy puddles" and "dinosaur".

But opening the presents during the get together was the biggest challenge for No Strings Attached actor Ashton, who is surprised by how things have changed since he was a youngster when it comes to toy safety.

"You have to have a tool box to get these toys... just to get them out!" he exclaimed. "They've ruined opening presents for kids. She opens it then it takes dad like a half hour to cut the plastic swizzle sticks off and break it... They make everything too safe now. When I was a kid we would ride in the back of a pickup truck on the wheel just trying not to fall out."

He also did an impression of how he and Mila strap Wyatt into her car seat, pulling his legs up towards his chin so he could almost lick his knees. This move didn't go smoothly though and Ashton ended up ripping a hole in the crotch of his trousers.

And, to keep fans on their toes, Ashton hinted the pair may be expecting a little boy, revealing: "(Wyatt) points to Mila and she's like, 'Baby brother' when she points to the belly and then she points to dad and she goes, 'Beer'."