Jack Black sprained his ankle during ‘Conan’ farewell musical number

"We came up with this big musical number that was gonna involve a lot of physicality, and I was gonna get injured in the middle of the musical number," Black explained. "I was gonna fake an injury, and then the paramedics were gonna come in and take me on a gurney out into the ambulance. And then I was gonna say, 'Hell no! Get me—I love Conan too much!' And I was gonna run back."

This, according to the 51-year-old and O'Brien, is what actually happened: They were pre-taping the bit Wednesday (June 23) where Black sprints back to the theater, and just when they thought they got what they needed, there was a suggestion to try it one more time.

Black ended up rolling his ankle on that last take.

"Today, I went and—just to be safe—I got an MRI," Black continued. "And they were like, 'Yup, nope, it's a real sprain. You've got some damage. You're gonna have to take it easy. No dancing. No running. No physical craziness for a while. You're gonna have to heal up.' And I was so bummed because I was like, I wanted to be the best guest of all time for your final episode, and instead, I am literally the lamest guest of all the time!"

O'Brien assured Black that the way it turned out was fitting. "Of course we think of a bit with Jack where Jack pretends to get hurt, and while shooting it, Jack gets hurt," the four-time Emmy-winning host said.

Black wouldn't go down without a fight, though. He clarified that the doctor did not say he couldn't sing, so he pulled a microphone out of his pocket and belted out an original ballad he'd written that day dedicated to the show—spoofing Frank Sinatra's "My Way."

 
Conan made its TBS debut in 2010. It followed Late Night with Conan O'Brien's NBC run from 1993 to 2009. Team Coco is set to premiere a weekly variety show on HBO Max at some point in the near-ish future.

Watch the 58-year-old's farewell monologue below.