Pete Wentz says Ashlee Simpson's breast milk tastes "soury and weird".
The Fall Out Boy rocker is not a fan of his wife's milk, but insists his newborn son Bronx Mowgli enjoys it.
He said: "The baby loves it, it's the only thing he's had a chance to have."
The star has also revealed his plans to become a father again and hopes to have a sizeable brood.
He said: "I want to have six now. I mean not six specifically, but I want more. I can't imagine that we're stopping, you know what I'm saying?
"This is like a Journey song, it's like the chorus is just going to keep coming."
Pete, 29, has also confessed he thought he was going into cardiac arrest when Ashlee was having the baby, but soon felt better when he saw his son.
He added to US radio station Sirius: "I had a scared moment right before she went into labour - I thought I was having a heart attack for real, like my heart started doing like a weird thing.
"But, the first time I held him. I just knew everything was perfect. Like everything was good - it was like Lego, you know what I'm saying? Like it all fit together."
