Stephen Colbert and Jimmy Fallon are Best Friends For Six Months (BFFSMs), so it's no surprise that they have been showing up on each others shows, having a couple laughs together. After Colbert auctioned off his portrait for Donor's Choose charity for $26,000, he announced that Fallon would be matching that amount with his own donation...without asking Fallon first. So last week, Fallon challenged his audience to donate $26,000, and if they did, Colbert would perform Rebecca Black's ubiquitous "Friday" on his program. Of course, he didn't ask Colbert first either. But last night, Colbert donned his best suit, kicked it in the front seat, kicked it in the back seat, and crooned the song with help from The Roots, Fallon, Taylor Hicks and the Knicks City Dancers. Fun fun fun fun! Check the video out below: