Pete Wentz's son, Bronx, could turn out to be just like his dad someday, but for now, he takes after a different Pete -- Peter Pan.
Us Weekly caught up with the Fall Out Boy bassist, 33, on Jan. 6 at an NBC Television Critics Association cocktail party in Pasadena, Calif., where the rocker gushed about his little boy's active fantasy life.
"He is definitely at an age where the imagination and the reasoning are just firing on a level [I can't understand]," the proud papa said of his 4-year-old son with ex-wife Ashlee Simpson. "I don't know if I ever had an imagination that good...When he's describing things or saying things, it's mind-blowing to me."
Another thing Bronx has in common with Peter Pan? An aversion to getting older.
"He was like, 'I don't want to be grown up,'" Wentz told Us. "He's like...'On my next birthday, I'm going to punch my birthday cake.' So he doesn't have to grow up. But I'm like, 'That's genius!' He doesn't even know how amazing that is! I'm like, 'You should punch your birthday cake! It's your birthday! Do it!'"
Of course, Bronx will have to get older someday. So is Wentz prepared to deal with a teenage version of his little guy?
"I mean, I'm [still] trying to conquer...putting away our toys after they're used," he said. "I'm going to get there, and I feel like by the time we get there, hopefully I'll have figured out where I sit on it and I can actually give decent advice."
"The thing that I've noticed is [that] a lot of kids tend to rebel against whatever exists [in their own families]," the tattooed rocker added. "I have friends who are in bands, and their kids are like hippies or whatever. So [Bronx will] probably be into math and be like, 'I'm not into tattoos.' And it's like, now I've got to figure out how to really do some of this essential math.'"
In the meantime, Wentz -- who will host Oxygen's tattoo competition series, Best Ink -- is happy to let his kid be a kid. In November, he and his ex-wife threw a superhero-themed bash for Bronx's 4th birthday at the Coop, a play space for children in Studio City, Calif. Also in attendance? Wentz's girlfriend, 24-year-old model Meagan Camper, and Simpson's parents, who are in the middle of an ugly divorce.
"The party was great," a source told Us of the party. "Super fun."