Want to look like an "Expert"? You're too late. The T-shirt worn by President Donald Trump's son as he arrived at the White House on Sunday evening is sold out.

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Barron Trump's shirt -- a gray ringer with blue around the sleeves and neck and "The Expert" written across the chest, and sold by J.Crew -- made waves on the internet as the first son arrived with his parents in Washington, D.C., following a weekend at Trump National Golf Club in Bedminster, New Jersey.

The shirt sells for $29.50 on the J.Crew website, which includes this description: “Whatever his skill set may be, this is the T-shirt that identifies him as the expert.”

Nearly instantly, imitations of Barron's shirt sprung up online, with at least two "The Expert" tees available through teespring.com.

A pool report also noted that 11-year-old Barron was holding a fidget spinner as he descended the steps of Air Force One when the first family landed at Andrews Air Force Base in Maryland.

Barron and first lady Melania Trump's arrival at the White House on Sunday marked the beginning of their first full week living in the White House. Until now, they have been staying at their residence in Trump Tower in New York as Barron completed the school year.