As with a lot of internet crazes, there isn't much to know about Barack Obama's yaaas gaga, except that it's all just a bit of fun!
It all started around two years ago when an Instagram user known as princeneptune filmed Lady Gaga arriving at a celebrity function and got overexcited by how she looked.
The exact quote: "Yaaaaaaas yes Gaga you look so good. Oh my god yes. Gaga you look beautiful."
A year after the clip was posted, it went viral and a new internet meme was born! President Obama got in the act through his official twitter account, when he posted princeneptune's exclamation in full.
On a more serious note, President Obama met Lady Gaga at the White House in May 2011 to discuss an anti-bullying campaign.
She also sang for the President at his 2013 inaugural ball: