Hope Santa has extra room in his sleigh! Neil Patrick Harris opened up about his 6-year-old son Gideon’s ambitious holiday wish list during a Wednesday, December 14, appearance on The Late Show With Stephen Colbert.

After the 43-year-old actor posted an Instagram pic of Gideon’s list (which included a bounce house and a life-size rocket ship!), Colbert had to ask how Harris was planning to make his little boy’s Christmas dreams come true.

"We live in the city," the New York City–based star, who shares Gideon and twin sister Harper with husband David Burtka, began. "That's what I said to him — 'Where are we supposed to put a life-size rocket?'"

Harris told Colbert that Harper is also hoping to find a few unusual gifts underneath the tree on Christmas morning. "Our daughter Harper asked for a pink karaoke machine," he said. "Pink? I get the karaoke part, but does it need to be pink?"

Soooo, Gideon wrote his holiday wish list...

A photo posted by Neil Patrick Harris (@nph) on

The How I Met Your Mother alum continued, "The other thing that she asked for was a doll house, but a life-size doll house for her. And I said … she's 48 inches tall. I said, 'Harper, a life-size doll house is just a house. You want me to get a house for you?' And she said, 'Yeah.' And I said,' What is it with these giant gifts? Where do we put a life-size doll house that's large enough for you or a person?' And she said, 'On the roof.'"

During his chat on The Late Show, Harris also spoke about his family’s love for Halloween and their annual group costume. Back in October, the adorable foursome dressed up as old Hollywood icons Groucho Marx, Marilyn Monroe, James Dean and Charlie Chaplin.

"What I think is going to be tough is when [the kids] start dictating what the costumes are gonna be," Harris joked to Colbert. "That's the arms race."

Watch the video above.

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