Side To Side Ariana Grande Feat. Nicki Minaj
Fun. are Nate Ruess, Andrew Dost and Jack Antonoff, a US indie pop band from New York.
The band have released a string songs back home but it's 'We Are Young' which is the first to put them in the US chart and at No. 1 no less.
The song is available to download in the UK now, can the boys match the success here that they've had in America?
Take a look at the video for 'We Are Young' and let us know what you think below...