Hilary Duff's son has picked out a name for his future baby sister-- and it is hilarious.

Duff shared with fans on The Late Late Show With James Corden what her son Luca, 6, wants to call the infant. Prepare yourself.

The Younger star explained that she and her partner were pretty open to various suggestions, and were willing to hear the young man out on his opinion.

Luca's suggestion? Cofant Croissant.

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Duff laughed as she told the late-night host that the names can only go together-- her son was insistent on using them both. To be fair, Cofant Croissant does have a certain ring to it...

Apparently the six-year-old has other ideas about his baby sister, as well. Hilary also spoke about how he has been telling his friends at school that his sister is part "red-butt monkey."

Duff, 30, announced via Instagram last Friday that she was expecting baby number 2 with partner Matthew Koma.

Luca, whose father is Duff's ex-husband and former NHL hockey player Mike Comrie, seems to be adjusting well.

Duff and Koma have been dating on and off, but their relationship was confirmed again when Hilary went on The Talk and joked about their rocky status. The former Disney star said that this was their third time dating and that hopefully the old adage, "third time's the charm" is working in their favor.

Duff's beau, Matthew Koma, has touched a lot of different music genres through his work. He co-wrote two of Zedd's EDM tracks and has collaborated with other famous DJ's to create a number of hits. He is also working on Shania Twain's latest album.

Sources told E! that Duff and Koma may be heading towards an engagement, but there is no official word on that from either of their camps. It seems like the pair is focusing on their expanding family right now, and taking care of Hilary's son, Luca.

Babies are everywhere in the Duff family! Hilary's sister Haylie, has just given birth to her second child. Haylie, 33, and her husband, Matt Rosenberg, welcomed a baby girl into the world on June 5th, 2018. The newborn was also greeted by her big sister, Ryan, age 2.

Congrats to all of the Duff clan on their expanding families!

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