At Donald Trump's inauguration, the public noticed that Barron Trump shook Joe Biden's hand and said something in his ear. People were curious to know what the youngest Trump said to the country's 46th president, but the message wasn't known — until now.

Must-know stories (and glorious gossip) from the D.C. mire.

Donald Trump had his youngest son, Barron, grinning from ear-to-ear after introducing the teen to his sports hero.

Trump's youngest is a bit of a mystery. A handshake with Biden at inauguration spurred many theories. Here’s what Barron said, according to Eric Trump

First son Barron Trump was “very respectable” when he crossed paths with former President Joe Biden at the Capitol Rotunda for his father’s inauguration in January,

Eric Trump revealed that Barron Trump told Joe Biden, "Congratulations and best of luck to you," during inauguration event.

The Trump family is messy, but Donald and his youngest son, Barron, seem pretty close. Donald probably won't approve of this polite move, though.

Donald Trump's son and the former President endured intense online speculation in January following their interaction.

It all comes as Barron, who attended his first year of college at New York University’s Greenwich Village campus, commuting from Trump Tower in Manhattan, is said to be “doing a semester” in Washington instead of at NYU’s main campus, where the Stern School of Business is based, according to People.