Flashy young Australian person Troye Sivan is keeping himself busy these days — so busy, in fact, that he will have appeared on The Tonight Show twice before the week is over. He released the excellent sophomore album Bloom. He acted in Boy Erased, a movie about a kid who gets sent to gay conversion camp. And he teamed up with fellow sideways-pop icon Charli XCX to release “1999,” a duet about being nostalgic for a time when Sivan himself was four years old.

Last night was the first of Sivan’s Tonight Show appearances for the week. On the show, he sat for an interview with Jimmy Fallon, talking about acting in Boy Erased and about working for the cause to make those conversion camps illegal. And he also rhapsodized about what Justin Timberlake used to do with his eyebrows during the NSYNC era, calling it “inspirational.”

And Sivan also performed alongside Charli XCX, the two of them doing “1999,” bringing the sort of showmanship that an ode to the teenpop era demands. We saw a bit of this when the two of them performed it at Radio City, but they’re both ridiculously fun and energetic performers, and it’s a blast to see them link up. Watch the interview and performance below.

“1999” is out now on the streaming services.