"My wife tells me (Mills & Boon) are a bit raunchy at times. What about this one; is there a bit of raunchiness?" Kochie asked the ex-wife of Prince Andrew.
The Duchess of York provided an equally cheeky response, saying, "Well, you know, the great thing Kochie is that you might, for the first time ever, have to pick up this book and read it. Your wife reads Mills & Boon but now you're going to read it".
As Kochie laughed at the playful dig, Fergie went on to clarify that it's "up to the reader to want to know whether it's raunchy or not", explaining that it's a very "authentic" romantic, historical novel.
WATCH: Fergie announces her first romance novel (Article continues after video)
During the interview, Nat jumped in to congratulate Sarah on her latest grandson, August, and the royal was quick to gush over the little one.
The author of 38 children's books told the morning show she was happy to have a "new customer", while also singing the praises of her two girls, Princesses Beatrice and Eugenie, for the way they continue to navigate public life.
And Sarah will be welcoming yet another grandchild to the mix soon enough, with her eldest daughter Beatrice expecting a baby later this year.
"Her Royal Highness Princess Beatrice and Mr Edoardo Mapelli Mozzi are very pleased to announce that they are expecting a baby in autumn of this year," an official royal statement read in May.
"The Queen has been informed and both families are delighted with the news."
Looks like Fergie will have to pen a new children's book for the little one!