And of course it's sweet and perfect.
With Jepsen at his side, Fallon and his "Late Night" house band The Roots play a variety of children's instruments, including a multicolored xylophone, bongos, a tone block and tambourine with Jepsen handling triangle duties, as they harmonize away on the hit song.
While all the "Call Me Maybe" covers have been fun, the trend is getting a little played out, and it simply can't get any better than Fallon, Jepsen and the Roots' goofy and wonderful backstage performance. Hopefully we'll be able to look back on it as the best and last. Check it out below:
When Jepsen swung by the MTV Newsroom last month, the pop sensation revealed that she loves all the viral video love, which has come from the Harvard baseball team, the Miami Dolphins cheerleaders, and many many others. "I have seen a few. It's pretty rad that people are participating and making their own versions," she told MTV News. "It makes my day to see it."
As for Fallon the musician, we certainly haven't seen the last of him. He's bringing his charm to the Internet tonight (June 8 ) at 8 p.m. for a live 60-minute "YouTube Presents" concert, where he'll be performing songs from his cheeky new comedy album, Blow Your Pants Off, due out next week.
He will also answer questions from Twitter users who tweet @LateNightJimmy with the hashtag #AskJimmy, so get your questions ready!