In mid-November, Metallica made a most peculiar appearance on The Tonight Show Starring Jimmy Fallon. Performing their transcendental hit "Enter Sandman," the group were joined by house band the Roots and Fallon as they delivered a unique rendition of the song using kids instruments. Now, James Hetfield has opened up about the performance and how much fun the group had.

Talking with Spotify's Metal Talks, Hetfield said the Jimmy Fallon appearance "showed up in our lap" and the band readily accepted and "had a blast doing that." Some fans gave Metallica flack for the goofy performance, but the singer / guitarist said, "You have to have humor, you have to… you've gotta laugh at yourselves, you've got to… not take yourself so seriously all the time. Stuff like that is just fun, and it lightens your heart and it humbles you as well."

The Metallica frontman also revealed that the band is sometimes "afraid to jam with certain people because we think we're not worthy enough; we're not great musicians." He noted that they were worried even though they were playing toy instruments designed for children and that Kirk Hammett kept practicing his part on the melodica over and over. "Dude, stop practicing it! Just go have fun, man. Go screw it up," Hetfield told Hammett.

Adding that "it's fun to give each other permission to screw up," Hetfield took delight in not being "under a microscope." He then referred to Metallica's typical live performances and how they can be tight sometimes and a little off at other times and that before hitting the stage, "we always remind each other that, 'Hey, mistakes are supposed to happen up here and it makes this gig unique. Don't be so hard on yourself. And if you're feeling down, just look at the other guys, and we'll carry you through.' So there's a freedom to f--k up in Metallica."

Metallica's long-awaited new record, Hardwired... To Self-Destruct, was released on Nov. 18 and ascended to No. 1 on the Billboard 200 charts in its debut week with 291,000 album units, which now incorporates digital streaming services. The band has booked stops all around the world and all tour dates can be found here.

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