If, like us, that's all you've ever dreamed of, today is your lucky day.
Fallon started off with a classic - 'Mr Brightside' by The Killers, while Ellen chose to go down a more sombre route with a Diana Ross track. She later realised she had to kick things up a notch of Jimmy's incredible performance of 'Watch Me' by Silento, so she cracked out Rihanna's 'BBHMM'. Needless to say, it was fairly incredible.
And that wasn't the only musical aspect of the evening - Jimmy and his other guest, Justin Timberlake, started the show by performing a six minute medley of hip hop songs in 'History of Rap #6'.