EXCLUSIVE: Jason Sudeikis Reveals Son Otis' Reaction to Becoming a Big Brother

Jason Sudeikis isn't the only one who's looking forward to adding a new member to his family.

ET's Lauren Zima caught up with the 40-year-old actor at The Angry Birds Movie premiere in Los Angeles' Westwood neighborhood on Saturday, where he adorably revealed that his son, Otis, is excited to become a big brother.

WATCH: Jason Sudeikis and Olivia Wilde Are Expecting Baby No. 2!

"He knows that it's something in an egg," Sudeikis said of his son's reaction to the baby news. "We just used metaphors in the movie [to explain it to him]. That's all. We explain everything through the movie."

In the 3-D animated comedy, Sudekis voices a bird named Red who has an angry demeanor, a characteristic the doting dad joked about sometimes displaying.

"We're both animated," he said, adding, "I grit my teeth. I think I inherited that from my father. When I get mad, it kind of manifests itself in my jaw."

Otis, who just celebrated his second birthday last month, already seems to be a big fan of the movie.

PHOTOS: Gwen Stefani Gleefully Supports Blake Shelton at 'Angry Birds' Premiere

"He has [seen it]," Sudeikis revealed. "This is the first movie that we've sat through the whole time together. He liked it a lot. I mean, he was riveted, which is pretty impressive to me. As I've told it to other parents, they were pretty shocked as well. But now he knows all the birds' names and everything. It's pretty adorable!"

Adorable, indeed!

An equally cute moment occurred when ET asked Sudeikis if he and his fiancée, Olivia Wilde, plan to have any more children.

WATCH: Jason Sudeikis Jokes He Won't Marry Olivia Wilde Until 'Weed Is Legal in Every State'

"Oh, God, I don't know," he said, smiling. "I haven't even thought about it. I'll say two until three becomes the number. Then four, and etcetera, etcetera."

The couple announced that they were expecting baby No. 2 last month. Wilde took to Instagram to share a super sweet photo of herself and Otis sitting on a bed, laughing and holding their bellies.

"Matching baby bumps," the 32-year-old Vinyl actress captioned the black-and-white snap.

WATCH: Jason Sudeikis Says Olivia Wilde is 'Good' With His Marriage Joke

Last week, Wilde hit the beach in Maui, Hawaii, rocking a tiny black bikini that perfectly showed off her burgeoning bump.

Watch the video below to hear more on her pregnancy.