Pete Wentz's son constantly asks him crazy questions.

The Fall Out Boy rocker - who has joint custody of four-year-old Bronx with his ex-wife Ashlee Simpson - can't believe how quickly the little boy has grown up and revealed he recently started asking him ''400 questions a day'' about the world.

The 33-year-old rocker told Ryan Seacrest on his KIIS-FM radio show on Friday (26.04.13): ''He's like a real human being now. It's kind of crazy.

''The protocol is ... you're supposed to say you don't know because if you start making it up they remember that stuff and then they say, 'Well, you said this and it doesn't make sense now.' And I'm like, 'Oh my god.'''

Pete admitted he often doesn't know the answers to some of Bronx's queries, such as the temperature of a volcano, and they have to seek answers elsewhere.

He said: ''And I'm like, 'I don't even know! We have to go to the book store.'''

The bassist, who is dating model Meagan Camper, also revealed that he regularly relies on his son's baby wipes to keep him clean on tour.

He said: ''I'll do that on tour like when we go on tour in Europe especially where you can't get showers as easily. I'll do a baby wipe-dry shampoo shower if that's what it comes down to.''

Pete recently praised Ashlee, 28, who he split from in February 2011 after two and a half years of marriage, for being an ''awesome'' mother.

He said: ''I feel like we both realise that we're parents and we're in it for our kid. That's made it really easy. I feel like, as a mom, she's awesome. She's an awesome mom and we get along really well when it comes to our kid now.''