EXCLUSIVE: Pregnant Chrissy Teigen and John Legend Joke That Their Baby Girl 'Might Be a Nightmare'

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John Legend's best-selling single, "All of Me," was written as an ode to his lovely wife, Chrissy Teigen. Now that the super-cute couple are expecting, the singer says they're "working on" writing a new song for when they welcome their baby girl.

"We need to figure out her attitude first," Teigen explained to ET's Carly Steel and Joe Zee while the happy parents-to-be walked the red carpet at the 2016 GRAMMYs on Monday.

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WATCH: Chrissy Teigen and John Legend Reveal They're Having a Baby Girl!

"She might be a nightmare. We don't know," Tiegen, 30, teased. "Everyone just assumes she'll be the sweetest thing on the planet [but] she might be a little hard."

According to the couple, they are still figuring out what to name their bundle of joy as well.

"We've written a few," Teigen shared. "We have maybe 10 options we just switch through. We can't pick. We've got to see her."

"We'll pick when we see her," Legend, 37, added.

WATCH: John Legend Talks Baby Names With Chrissy Teigen

Another thing that has to wait until Teigen gives birth is getting to watch the perfect pair face off on Teigen's hit show, Lip Sync Battle.

"I can't," Teigen said, when asked if she'll be taking the stage anytime soon. "At least not during my sobriety. There's no way I could."

That being said, she did reveal that when she finally does perform on the show, she's already chosen the artist.

"Mariah [Carey]. Probably 'Hero'. Something that means something to me," Teigen shared.

As for Legend: "I only rap when I lip sync, so it has to be a rap."

WATCH: Chrissy Teigen Reveals the Craziest Place She and John Legend Have Had Sex

While the two are getting ready for the new addition to their family, they're also adding some additions to their new home, which is currently being remodeled. In fact, their new abode used to belong to Rihanna, and according to Teigen, they are still getting some of the 27-year-old singer's mail.

"Rihanna, if you're watching, we have some of your mail!" Teigen joked. "You have a $19 credit towards a car purchase, I believe."

WATCH: John Legend Reveals Chrissy Teigen’s Pregnancy Cravings

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