Foo Fighter's front man Dave Grohl took over hosting duties for Jimmy Kimmel Live on Halloween night dressed as David Letterman. But Grohl couldn't just host. Instead, he enthusiastically backed up Kristen Bell on a thrash metal version of Frozen song "Do You Want to Build a Snowman" mashed up with Metallica hit "Enter Sandman." While Grohl was dressed as David Letterman, full beard and all, he did his best to imitate Metallica's Lars Ulrich behind the kit while Bell channeled her inner James Hetfield on the mic.

While Dave Grohl's Halloween costume was tough to beat, Kristen Bell came out as Magnum P.I. (Tom Selleck}, complete with mustache, wig, Hawaiian shirt, and some sweet chest hair. During the main segment interview, Grohl expressed how happy his kids were that he got to hang out and interview Kristen Bell, aka Elsa from Frozen. Bell was on the show to promote the upcoming A Band Moms Christmas and the two got into the subject of jamming, which then led to Bell taking the mic and Grohl jumping behind the drums.

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"Do You Want to Build a Snowman" started off faithful to the now Disney classic, but later took a heavier turn when Dave Grohl jumped behind the drum kit. The Frozen song got a heavy metal makeover that kept getting heavier as Kristen Bell morphed her voice from angelic singing into the familiar bark of Metallica's James Hetfield. As the song intensified, it took a huge left turn into Metallica's "Enter Sandman" with David Grohl bashing on the drums and Bell delivering an impressive Hetfield impression. The only thing that could have possibly made the collaboration better was if Kristen Bell would have strapped on a Gibson Explorer to truly channel the Hetfield mojo.

The decision for Dave Grohl to dress as David Letterman for the Halloween episode of Jimmy Kimmel Live came about since Letterman is a huge fan of the Foo Fighters. In February 2000, Letterman underwent emergency quintuple bypass surgery following a heart attack. After being sidelined for five weeks, the host asked Foo Fighters to appear on his first post-surgery show to perform "Everlong," their single that was reportedly instrumental in the host's recovery. Introducing the Foo Fighters for that performance, Letterman said "my favorite band playing my favorite song." The Foo Fighters also played Letterman's final night of hosting The Late Show. In addition, David Letterman is one of Jimmy Kimmel's biggest comedic inspirations, so the costume was really more than just a Halloween stunt and more of a tribute.

Dave Grohl didn't stop the collaborations with just Kristen Bell. The original shock rocker Alice Cooper also showed up. The Foo Fighters jumped on stage to back Alice Cooper and rip through two of his most legendary songs from the 1970s, "The Ballad of Dwight Fry" and "Killer." All in all, Dave Grohl did quite the impressive job taking over hosting duties from Jimmy Kimmel, leaving many to wonder if there's anything that the musician can't do. Check out footage of Dave Grohl and Kristen Bell ripping "Do You Want to Build a Snowman" below, courtesy of the Jimmy Kimmel Live YouTube page.