They might be one of the  biggest live draws in the world, have more money than some third world countries, and currently have the biggest rock debut in more than two years, but that doesn’t mean Metallica still aren’t nervous about their musical ability. In the latest installation of Spotify’s Metal Talks, James Hetfield says that when they went on The Tonight Show Starring Jimmy Fallon to play “Enter Sandman” with The Roots using classroom instruments, they were afraid to mess up.

“We’re literally afraid to jam with certain people, because we think we’re not worthy enough. We’re not great musicians. Even with those little flutes and stuff I was worried. Kirk was practicing the song on this little recording thing. It’s like, ‘Dude, stop practicing it – just go have fun. Go screw it up!’ You’ve got to laugh at yourselves. You’ve got to not take yourself so seriously all the time. The Jimmy Fallon thing showed up in our lap, they said, ‘You want to do this?’ We had a blast. Stuff like that is just fun. It lightens your heart and it humbles you as well.”

Granted, if there’s one band that might be more professional than Metallica, it could be The Roots, but it’s hard to take yourself seriously when you’re playing a plastic clarinet, a melodica and a toy guitar. And hey, worst case scenario, if they messed up, they could have started giggling, like their host.