Washington: A caller trolled US President Joe Biden during a White House Christmas Eve event on Friday who said “Let’s Go Brandon” in a coded insult that has become a rallying cry for supporters of Donald Trump.

The incident took place after Biden and First Lady Jill Biden spoke by video conference with North American Aerospace Defense Command (NORAD) officials, who track Santa’s travel across the globe, which quickly went viral online. After being assured of St Nick’s progress, the President fielded calls from several American families.

One man identified himself as Jared, a father of four. Biden spoke briefly with the caller’s children, asking what presents they wanted for Christmas and telling them they needed to be in bed before midnight. He also remarked on how he and Jared both had sons named Hunter. Wrapping up the call, Biden wished Jared a wonderful Christmas.

I hope you guys have a wonderful Christmas as well, Merry Christmas, and let’s go Brandon!” Jared replied. Let’s go Brandon, I agree, returned Biden, without reacting to the dig. It was not immediately clear if the president had understood the reference, though Jill Biden chuckled uncomfortably and rolled her eyes. Biden asked Jared where he was calling from, but by then the call had been disconnected. A clip of the moment spread widely on social media, with some praising the president for his calm response.

Let’s Go Brandon is a euphemism for a vulgar insult that originated when a reporter at a NASCAR event misheard a chant of F* Joe Biden while interviewing driver Brandon Brown in September. Since then it has been taken up as a political slogan by supporters of Trump, Biden’s predecessor.

The Santa tracker presented by NORAD dates to 1955, when a Colorado newspaper advertisement misprinted a phone number to connect children with Santa and mistakenly directed them to the military nerve center hotline.