barack obama
US President Barack Obama speaks during his last press conference at the White House in Washington, U.S., January 18, 2017. Reuters/Joshua Roberts

A light-hearted exchange between US ex-presidents George W Bush and Barack Obama while Bill Clinton was speaking is going viral. The brief banter between 43 and 44 has been immortalised in a GIF by amused social media users.

Five past American presidents – Bush, Obama, Clinton, George HW Bush and Jimmy Carter – all gathered together for the “Deep from the Heart: The One America Appeal for Hurricane Relief” at the Texas A&M University on Saturday evening. The event was held so they could pay tribute to the volunteers and raise money for the victims of Hurricanes Harvey, Irma and Maria.

All five of them got a chance to address the crowd on stage. While it was Clinton’s turn, the younger Bush was seen leaning toward Obama and told him something that made his successor laugh.

What Bush said to Obama is a mystery, but whatever it was, he appeared to be so proud of it. As Internet users have noted, Bush looked so smug that his comment, which people assumed was a joke, made Obama giggle. The joke, whatever Bush told Obama, appeared to be really funny as Obama could be seen still trying to regain his composure after cracking up. The moment went viral online, with Twitter account @ClassicDadMoves noting that Bush made a “dad move.”

The relief concert also featured performance from Lady Gaga, who revealed she donated US$1 million (AU$1.28 million) to the cause. Her donation was specifically designated for a program that focuses on mental health.

“We must also recover mentally, as well as physically,” the Grammy Award-winning artist said. “We need to help these survivors recover from the trauma of losing their homes, losing their lives, watching everything get washed away.”

Country music band Alabama, Sam Moore, Yolanda Adams, as well as Texas musicians Lyle Lovett and Robert Earl Keen also performed. US President Donald Trump recorded a video message that was played during the event.