On Wednesday night's episode of The Tonight Show, Billy Joel, Jimmy Fallon and J.K. Simmons treated the studio audience to an impromptu performance of "The Longest Time," one of Joel's classic hits. They belted it out for fun while they were filming local commercial promos. Needless to say, it was a delight and they crushed it.

When Fallon isn't having celebs compete in lip sync battles, they do hilarious covers of songs, like a barbershop quartet version of "Bitch Better Have My Money." But this was even more impressive, because it was obviously not rehearsed:

Sources: The Tonight Show Starring Jimmy Fallon