Republican presidential nominee Donald Trump has no shortage of critics. But the most outspoken – and funniest – is arguably none other than President Barack Obama, who has mastered the art of taking jabs at The Donald with barbed jokes. Here are his best takedowns of Trump so far.

1. Conspiracy-Theoriest-in-Chief

Obama had a lot of pep during the 2011 White House Correspondents Dinner. Earlier that week, the state of Hawaii had released his long-form birth certificate, putting an end the arguably racist ‘birther movement’ led by Donald Trump. The birthers argued that Obama wasn’t born in America, so he was ineligible to be president. But only someone who sleeps in a tinfoil bed could cling to that conspiracy after Obama’s records were released.

And Obama wanted to share that moment with Trump.

“No one is happier to put this birth certificate matter to rest than The Donald. And that’s because he can get back to focusing on the issues that matter. Like did we fake the moon landing? What really happened in Roswell? And where are Biggie and Tupac?”

2. Backing Trump’s Leadership

At that same 2011 dinner, Obama backed Trump’s leadership credentials.

“All kidding aside, we all know about [Trump’s] credentials and breadth of experience. For example…on an episode of The Celebrity Apprentice, at the steak house, the men’s cooking team did not impress the judges…and there was a lot of blame to go around. But you, Mr. Trump, recognized that the real problem was a lack of leadership. So ultimately you didn’t blame Lil Jon or Meatloaf. You fired Gary Busey. And these are the kind of decisions that would keep me up at night.”

3. Weighing in on the Wall

Trump hasn’t served a day in the Oval Office, but the White House is already having to clean up his messes. Last April, President Obama revealed that he has to spend time discussing the implications of The Donald’s foreign policy with world leaders who are worried about a possible Trump presidency.

“I am getting questions constantly from foreign leaders about some of the wackier suggestions that are being made,” Obama told the White House press corps last April.

Those suggestions of course include building building a giant wall along the Mexican-American border wall and to preventing cross-border remittances – i.e. blocking people living in the United States from sending money to Mexico.

“Good luck with that,” Obama quipped.

4. The Millennial President

When endorsing Hillary Clinton last July, Obama suggested that every millennial you know has basically the same presidential qualifications as Trump, who has mastered riling up supporters with his outrageous posts on Twitter.

“Everybody can tweet, but nobody actually knows what it takes to do the job until you’ve sat behind the desk,” Obama told supporters at a rally in Wisconsin. “I mean, Sasha [Obama’s younger daughter] tweets, but she doesn’t thereby think that she thereby should be sitting behind the desk.”

He also hammered Trump’s foreign policy credentials while praising Clinton’s work as secretary of state.

“America is really great,” he told the crowd, countering Trump’s campaign slogan. “Part of the reason for that is because we had an outstanding secretary of state. Part of the reason is that Hillary understood and continues to understand that a bunch of tough talk doesn’t replace the hard work of diplomacy. A bunch of phoney bluster doesn’t keep us safe. And she understands that we can’t retreat from a world that needs American leadership.”

5. Vetting Trump’s Business Record

Obama has spent years criticizing Trump’s credibility. But he doesn’t expect Trump will change his ways and start taking things like foreign policy seriously.

“The Donald is not really a plans guy,” he said at the Democratic National Convention last July. “He’s not really a facts guy either. He calls himself a business guy, which is true. But I have to say, I know plenty of businessmen and women who have achieved remarkable success without leaving a trail of lawsuits, and unpaid workers and people feeling like they got cheated. Does anyone really believe that a guy who’s spent his 70 years on this earth showing no regard for working people is suddenly going to become your champion?”