'Is this a thing?': Ariana Grande's reaction to 'That's My Jam' game tickles host Jimmy Fallon

Jimmy Fallon is giggling gleefully because President Joe Biden has shared the "Tonight Show" host's pandemic-themed holiday song, just hours before Biden gave Fallon his first late-night interview as commander in chief. 

"The president just tweeted about my song so I'm freaking out," Fallon says of "It Was A … (Masked Christmas)," an upbeat track promoting COVID-19 booster vaccines featuring Fallon, Ariana Grande and Megan Thee Stallion. Fallon has experienced COVID-19 first-hand, announcing on Instagram Monday that he tested positive for the disease in December and has recovered after experiencing mild symptoms.

Music, at the heart of Fallon's new game show "That's My Jam," has been a constant in his life. He remembers being raised on radio. 

"My dad had me and my sister climb into our attic and hang speaker wire to build a giant antenna for our house (to get radio reception)," says Fallon, 47. "Probably not the safest thing for children. The whole house is basically a microwave." 

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The humorous tracks played by Dr. Demento (aka Barret Eugene Hansen) inspired Fallon to compose music of his own. 

"I got into writing novelty songs and funny songs and comedy songs," he says. "So that was always part of my life, doing impressions and being into music." 

NBC's "That's My Jam" (premieres Monday, 9 EST/PST) pits two teams of paired celebrities, who go head-to-head for the charities of their choice in music-themed games, some of which have been featured on "The Tonight Show." 

In "Air Guitar," a correct answer to a trivia question sends a blast of air and confetti shooting at your opponents' faces. A wrong guess sends the rush of air your way. Don't know the lyrics for “Slay It, Don’t Spray It”? Then water will shoot out of your microphone. A Mixtape Medley showdown between powerhouses Kelly Clarkson and Ariana Grande in the series' previously aired sneak peek resulted in tears, Fallon says, after Clarkson slayed Whitney Houston's "I Will Always Love You." "People were crying in the audience," he says. "I've never seen anything like it."

Chance The Rapper, Bebe Rexha, Josh Groban and Normani are among guests for the debut season, but professional musicians aren't the show's only successes. Fallon is impressed with performances by Kate Hudson, Taraji P. Henson and Anthony Anderson.

Fallon shares his dream guests, favorite games and whether he's eyeing an end to his "Tonight Show" tenure:.

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Question: How did the idea for "That's My Jam" come about? 

Jimmy Fallon: With COVID and everything, this got pushed back. This idea is probably three years in the making, and we based it off of the musical games we play on "The Tonight Show," but with a more prime-time budget, and the best guests we can book. 

Q: Why did you want to host, rather than just produce? 

Fallon: I just knew what the show was. I had a vision of it, and I thought it'd be faster and more efficient if I just hosted it. "I know where this is going to go, and I've done these games on 'The Tonight Show,' and I think it would be more efficient if I just hosted it." Who knows if I'll host the next season, but just to kick it off. I also have the relationships with all these guests. So I thought that would be the smartest move. 

Q: Which game is the most fun for you? What do you find the most entertaining? 

Fallon: Watching the "Wheel of Impossible Karaoke" and watching these celebrities do weird versions of songs where they get to actually perform and sing. I'm a fan of any musical performance, so when they get to sing in front of this awesome band, Adam Blackstone's band ... (it's) like karaoke at the greatest level.

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Q: Which games torment the guests the most?

Fallon: Ariana (Grande)'s wig blew off (during 'Air Guitar'). We make everyone wear wigs, and this little wig she had blew off, and it was loud and she actually said, "What is going on? Is this a thing?" I love that question: "Is this a thing?" Like, "Is this a thing you do to people? What is this?" It really made me laugh. "Is this a thing?" I go, "Yeah, it's a thing. This is the game."

Guests can know that everything's safe. They can know that they won't look bad, even as bad as they think they'll look. They'll be soaking wet, they'll have stuff dumped on them, we'll change the music so that their voice is out of tune – whatever we do. But it's all in fun and games, and that's really the whole point of the game is just to have fun. 

Q: Who are your dream guests?

Fallon: There's always (Justin) Timberlake, in my back pocket, ready to call. Tina Fey would be great, Amy Poehler, Adele. They're all fun. I've done bits with all of these people on ("The Tonight Show"). Madonna would be great. Now that people know what the show is, it's kind of easier, people go, "OK, I can do that." 

Q: Your "Tonight Show" contract was recently renewed (for five years in May). Have you thought about how much longer you would like to stay? 

Fallon: We're doing well in the ratings. People are interested in our show. So as long as we keep people interested. I love doing it. I'm still interested in people, and I'm interested in entertaining. I love my job, and I love the people I work with. I think I'm here for the long haul. 

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