Constance Wu is giving us a glimpse into her life as a new mom.

Appearing on The Tonight Show Starring Jimmy Fallon, Wu gushed about her nine-month-old daughter.

“She’s the best, she’s the best. She has a full head of hair. She has a blue butt.”

When Fallon moved the interview along without acknowledging her daughter’s colorful trait, Wu wasn’t having it.

“You didn’t ask me about the blue butt, Jimmy!” Wu playfully interrupted. “I thought that you might be curious about the baby with the blue butt.”

“Yes, her butt is the color blue,” Wu went on to explain. “There’s this thing, I had never heard of it before, but it’s called a ‘Mongolian spot.’ And apparently, it happens in a lot of Asian babies, and my boyfriend and I are both Asian, and it’s where your butt is blue for the first two years of your life and then it just goes away.”

Constance Wu’s Baby Daughter Has a Blue Butt | The Tonight Show Starring Jimmy Fallon

According to the Mayo Clinic, the condition has several names: dermal melanocytosis, slate gray nevus, or a Mongolian spot. The medical community is largely moving away from the latter name, though, for its outdated and racist connotations.

Dermal melanocytosis is common in babies of color, especially in Black and Asian children. Like Wu said, it usually fades in early childhood with no treatment.

“It’s a very special thing and it’s not something that she gets to show off while she’s walking down the street, not that she’s walking yet,” Wu added.

Later in the interview, Fallon asked the “Crazy Rich Asians” actress if her boyfriend, musician Ryan Kattner, played music for their daughter.

“He actually wrote a song about her blue butt,” she replied, “so that will be on his next album.”

Wu and Kattner have largely remained private when it comes to life with their daughter. We’re loving learning more about their little family—and seeing Wu gush over her daughter.

Let’s be honest: we know what it’s like to memorize each birthmark, curl, and giggle. Wu is one proud mama, eager to talk about her daughter’s adorable and one-of-a-kind butt.