ICYMI: Krasinski co-created the hit Jimmy Fallon segment. John Krasinski, best known to fans of NBC's “The Office” as Jim, came on “Late Night with Jimmy Fallon” Tuesday to talk about the long-running. John Krasinskis Lip Sync-Off with Jimmy Fallon: Watch Here! - He's earned quite the reputation for his hilarious brand of humor, and John Krasinski brought his. John Krasinski, best known as Jim Halpert from The Office, on Jimmy Fallon's The Tonight Show doing a Lip Sync. Tags: lip the-tonight-show the-office sync off with john krasinski and jimmy fallon katy perry run dmc john-krasinski jim-halpert jimmy-fallon funny lulz. Lip Sync Battle. Here's what Krasinski had to say about the origin of Lip Sync Battle: John Krasinski and Jimmy Fallon faced off for the first "Lip Sync Battle" in.