While most mothers might avoid the question, Hawn proved she's not like regular moms -- she's a cool mom -- and not only talked about his behind, but took it a step further.
"I laughed so hard. That guy makes me laugh. Doesn't he have a gorgeous tuchus?" Hawn said with a laugh. "When I had him circumcised, the doctor said, 'You'll be happy to know I had to get a bigger clamp.' A bigger clamp! Of course, I was crying too, because I knew he was going to cry."
"It was a double edge sword, so to speak," she added. "This isn't televised, right?"
Oliver wasn't the only one of her children Hawn was asked about during the show, as a caller also wanted to know what she thought about daughter Kate Hudson dating Nick Jonas.
"As long as the kids are having fun, I don't care," she revealed. "He's a very nice guy, a good person."
When asked if she ever cooked him dinner, Hawn said she hadn't ... but "would have, if it lasted long enough!"
While Hawn was game for anything, Schumer had a hard time playing Plead the Fifth. She easily answered Cohen's first question, but avoided the final two.
Up first: "What's the rudest thing you've done in the bedroom?"
"Well it was when I saw that a guy had an uncircumcised penis and it was too big and I went, 'Peace!'" she replied. "I was like, I'm not going to be deformed because I had sex with you once. That's what 'Get Out' should have been about!"
She was then asked to play a round of Shag, Marry, Kill with a trio of male comedy mentors -- Jerry Seinfeld, Chris Rock and Louis CK -- and to reveal the most "offensive or bizarre thing a male comedian has said" to her.
No such luck with those last two.
Hawn and Schumer's film, "Snatched" is now playing in theaters.