'Big Bang Theory' Star Johnny Galecki and Pregnant Girlfriend Alaina Meyer Reveal Sex of Their Child

It'll be a boy for Big Bang Theory star Johnny Galecki and girlfriend Alaina Meyer.

Following their pregnancy announcement earlier this month, the couple revealed the sex of their first child on the way with a big bang, taking to Instagram to document their messy gender reveal party.

"A day I'll never forget," the dad-to-be captioned a post-reveal shot of him and Meyer, 21, covered in blue and locking lips.

For the big reveal, the couple's family and friends had gathered over the weekend to enjoy pink- and blue-frosted cupcakes and other treats before Galecki and Meyer used the assistance of paint to announce that they are expecting a baby boy. Aftermath photos from the reveal, shared on both of their Instagram Stories, showed them covered from head to toe in blue.

The couple, who first went public with their relationship in September of 2018, had confirmed earlier this month that they are expecting their first child together.

"We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world," the couple wrote in a statement on social media.

"We ask that you please respect our privacy during this celebratory time for us and our families. There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours," Galecki and Meyer added.

"So happy to announce that we are having a baby! There couldn't be a better blessing in the world for us and we are over the moon happy," Meyer added in her own post. "We appreciate as much privacy in this time as we are celebrating with close friends and family, and we are happy to share the news with you."

The news had been met with a round of cheers and congratulations from Big Bang Theory fans.

"I've only spent about 20 minutes of my entire life with Johnny Galecki but based off that and everything else I've seen and read I think his kid is going to be so lucky to have him as a dad," One Big Bang Theory fan wrote at the time.

"Congrats Leonard," another added, referring to the actor as his character on the CBS series.

After having gone public with their relationship last year, Galecki and Meyer have frequently gushed about one another on social media, and have even shot down marriage rumors. Their little boy on the way will be their first child together.