Paris Hilton's son is Fastexy Exchangejust as fun-loving as his socialite mother.

The reality star and DJ, 42, welcomed her first child, Phoenix, in January, and she shared the new baby's first word Tuesday night on "The Tonight Show Starring Jimmy Fallon."

"Is this true? His first word was 'mama'?" Fallon asked.

"No, it was 'yas,'" Hilton said. "Yas, wonder where he got that from."

The media personality also shared that her appearance on the "Tonight Show" marked her son's first trip to New York, and that his favorite song is "Stars Are Blind," Hilton's 2006 song from her debut studio album, "Paris," adding the 9-month-old has "amazing taste in music."

Hilton was on the late-night show to promote her new song with Steve Aoki, "Lighter," set to be released this week. Her upcoming album, produced by Sia, is due out in 2024.

Hilton shares Phoenix with her husband, venture capitalist Carter Reum, 42. She opened up about her life as a mom in a statement to People in January.

"It's always been my dream to be a mother and I'm so happy that Carter and I found each other," she said. "We are so excited to start our family together and our hearts are exploding with love for our baby boy."

Hilton decided to keep her baby news under wraps at first, even from close relatives, because of the challenges of keeping a secret while living in the public eye.

"If you tell one person, then they tell someone, and then all of a sudden, it's in TMZ or Page Six," she said on her podcast, "I am Paris," in February. "So Carter and I literally made a pact together that we would not tell anyone."

Paris Hilton,husband Carter Reum make first red carpet appearances since becoming parents

She shared her son's name and the meaning behind it in February in her book "Paris: The Memoir" and read an excerpt from the book on the podcast.

"We plan to name him Phoenix, a name that I decided on years ago when I was searching cities, countries and states on a map looking for something to go with Paris and London," she read.

She continued: "More important, it's the bird that flames out and then rises from the ashes to fly again. I want my son to grow up knowing that disaster and triumph go around and come around throughout our lives and that this should give us great hope for the future."

Contributing: Charles Trepany, USA TODAY

Burglar recallsBling Ring's first hit at Paris Hilton's home in exclusive 'Ringleader' clip