Jimmy Fallon kicked off his era as host of "The Tonight Show" by revealing a "friend" made a bet with him that he'd never land the job of hosting the show.

Fallon settled in behind his new desk after his opening monologue and thanked fans for their years of support before calling for that "friend" to make good on their bet.

"To my buddy who said that I'd never be the host of The Tonight Show - you know who you are," Fallon then said to the camera. "You owe me $100 buddy!"

Following his call-out, actor Robert De Niro emerged from backstage with a hundred-dollar bill in hand and begrudgingly slapped it down on Fallon's desk before walking away.

Jimmy was then visited by numerous other stars, including former "Saturday Night Live" co-star Tina Fey, Lindsay Lohan, Seth Rogen, Mike Tyson, Mariah Carey, Kim Kardashian, a very scantily-clad Lady Gaga, Sarah Jessica Parker and new late-night rival Stephen Colbert, who made his payment in pennies, posed with Fallon for a selfie and shouted, "Welcome to 11:30, b*tch!"

Fallon's first guest was actor Will Smith, and the musical guest was U2.