"A pretty sizeable percentage" of world leaders have lost their minds, according to President Obama. "Part of what happens is these guys, I think the longer they stay in office, the more likely that is to happen," he told comedian Jerry Seinfeld, in an admittedly tongue-in-cheek interview.

"At a certain point your feet hurt, and you're having trouble peeing, and you have absolute power," he joked.

The president was being interviewed for Seinfeld's long-running internet series Comedians In Cars Getting Coffee. While Obama is not technically a comedian, Seinfeld reasoned that he'd "gotten off just enough funny lines to qualify for getting on this show".

And so he proved: much of the interview was quite funny, but in the mix were a few serious questions.

When Seinfeld asked, "How many world leaders do you think are just completely out of their mind?" the president seemed to take the question seriously.

He had a few choice words for his political colleagues in Congress – the American equivalent of the Houses of Parliament. He said: "There are going to be some folks there that are foolish," he suggested, naming no names.

He also admitted that he'd like to be considered for a position on Mount Rushmore, the landmark in South Dakota with the faces of four celebrated presidents carved into it.