While visiting Jimmy Kimmel Live last week, U2 talked about the inspiration behind their Joshua Tree album, their love for America and surprised the audience with a performance of one of their biggest hits.

“We love America,” Bono told the late night host. “For Irish people, America’s the promised land.”

But the reason behind the title of the album, wasn’t entirely serious.

“He couldn’t say ‘Joshua Tree’ … which is one of the reasons we called it ‘Joshua Tree’ – because it kept making us laugh.”

Watch the band’s surprise performance of “I Still Haven’t Found What I’m Looking For” below.