The 'Vegas' actress' two kids helped her reveal the gender.
Molly Sims had her cute kids help announce the sex of her baby-to-be.
In a video posted to her Youtube channel on Tuesday, the former Las Vegas star's 4-year-old son, Brooks, nearly spills the news, but gets excited when his mother opens a big box to reveal a bunch of blue balloons.
"We're having a boy!" the 43-year-old actress exclaims as her 1-year-old daughter, Scarlett, stands alongside her.
"We're going to have a baby brother," Brooks chimes in before singing the Batman theme song.
"Brooks is really excited to be having a baby boy," Sims says. "He's already named it Jack and the Beanstalk-Batman. That's his full name. It's been really sweet to see him so involved."
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Sims' husband, Scott Stuber, is also excited about having another son. "When they first told my husband we were having a boy, I swear he almost started crying," she gushes. "It's happening. We're having a boy."
While at the Casamigos Tequila Halloween party a few weeks ago, Sims told ET that she already has some names in mind. "If it’s a boy, I love Wesley and Finley and Dutch and Wilder," she shared.