Foo Fighters frontman Dave Grohl sat in for Jimmy Kimmel during the taping of the late-night host's talk show yesterday — and fittingly for a Halloween episode, the night found him interviewing celebrity guests and making music in costume.

As captured in the clip above, Grohl's big interview for the evening was actor Kristen Bell, who's currently making the publicity rounds for her new movie A Bad Moms Christmas — but who, as Grohl excitedly pointed out, will always be Elsa from Frozen to millions of kids who loved the animated Disney hit.

"Me being here with you — it's the biggest deal to my kids," said Grohl, dressed up like retired late-night legend David Letterman. "If I were to jam a song with you, I would become the coolest dad."

"I would jam with you," responded Bell, who came dressed as the title character from Tom Selleck's hit '80s TV show Magnum, P.I. "I would!"

After that, there was only one thing left to do: perform a mashup of the Frozen soundtrack anthem "Do You Want to Build a Snowman" and the Metallica classic "Enter Sandman," with Grohl — still rocking a big fake beard — behind the drum kit and a mustachioed Bell taking the mic. The Foos, of course, have their own promo rounds to make these days on behalf of their new Concrete and Gold LP, but none of that will matter to Grohl's kids as much as this singularly surreal late-night jam.

Bell wasn't Grohl's only guest of the evening, either — Alice Cooper stopped by to share his backstage pre-show ritual, talk about the well-known old photo of himself standing next to Kentucky Fried Chicken pitchman Colonel Sanders, and continue Jimmy Kimmel Live!'s long feud with actor Matt Damon by showing Cooper throwing knives at a photo of the star. Check out Cooper's Kimmel visit below.

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