When Stephen Colbert auctioned off his portrait for Donor's Choose charity for $26,000, he was delighted to announce that Jimmy Fallon would be matching that amount in a donation of his own. Only problem was, Colbert made the promise without telling Jimmy.

That is the newest chapter in the Colbert/Fallon bromance fable that has been playing out across late night screens for the last few weeks. It's been a genuine delight to see the cross promotion between the shows in the service of charity, but Fallon kicked it up a notch last night. After a broken-hearted Colbert left the stage telling Jimmy to consider what he had lost, Jimmy issued a brand new (unapproved by Stephen) challenge: if Fallon's audience can raise $26,000 for the charity, Stephen will return to "Late Night" and sing a rendition of Rebecca Black's "Friday" accompanied by The Roots.