Foo Fighters frontman Dave Grohl hosting Jimmy Kimmel Live! and jamming with Kristen Bell on a mashup of "Snowman" from Bell's 2013 animated hit, Frozen, and Metallica's "Enter Sandman" wasn't strange enough.
It was also Halloween so both were in costume: Grohl was dressed as modern-day David Letterman—yes, beard and all; Bell was dressed as Tom Selleck as Magnum P.I.
For the bit, Grohl got Bell to sing after explaining to her how much it would mean to his two young daughters to hear him jam with the voice of one of their favorite cartoon characters, Elsa from Frozen.
Check out the jam session above.
Watch Grohl's monologue below.