If you've been following the saga of "BFFs for six months" Stephen Colbert and Jimmy Fallon, you'd know that last week Colbert pledged $26,000 of Fallon's money to the charity DonorsChoose.org, but without asking Fallon first.

Fallon responded Monday to this by announcing that if he could raise that $26,000 from the public, then Colbert would be forced to appear on 'Late Night With Jimmy Fallon' and sing Rebecca Black's viral sensation 'Friday' with The Roots.

"What the f**k?" Colbert said on Tuesday's 'The Colbert Report' (Weeknights, 11:30PM ET on Comedy Central), after playing the clip of Fallon saying that $26,000 buys the public a singing Colbert.

"I never said I'd sing, and what the hell is this 'Friday' song?"

However, as often is the case with Colbert, things aren't what they first seem, and Colbert then plugged the websites where you can donate the money, under the guise of telling his audience to avoid them.

"We have to stop this man," Colbert explained. "Because if Jimmy Fallon reaches his goal, I will be forced to give the performance of a lifetime."

Watch the full episode here: