"There are a lot of things that go into it. Speed is a big part of it," he says.
Pete Wentz iheart radio music festival

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Although Pete Wentz‘s new baby boy is too young to understand his father’s occupation, the Fall Out Boy bassist’s oldest son, Bronx, knows what his dad does — and he’s not impressed.

“[He] comes to our shows, but it’s the equivalent to me going to my dad’s job when I was a kid. At the end of the day, it’s Dad’s job,” Wentz told PEOPLE at the iHeartRadio Music Festival in Las Vegas on Friday.

“All I am to him is his dad. When he sees people want to take a picture with me, he thinks it’s hilarious.”

In fact, adds Wentz, his 5½-year-old is completely “uninterested” in his dad’s rock star status.

But music isn’t the new dad’s only strong suit. If there was a trophy in the sport of diaper changing, Wentz — who welcomed his second son, Saint Lazslo, in August — would be the reigning champ, he jokes.

“I’m a great diaper changer,” he says. “There are a lot of things that go into it. Speed is a big part of it.”

As for daddy duty the second time around, Wentz says he’s prepared for what lies ahead.

“I know the phases now, I know that they change and you are on the roller coaster and there are ups and downs and you’re not falling off the ride,” he explains.

— Mark Gray