Kristen Bell Dave Grohl Enter Snowman
Kristen Bell sings as Tom Sellek, with Dave Grohl as David Letterman in the background. There's a caption I never thought I'd write. ABC

On Halloween night, US talk shows went all out to celebrate the spookiest night of the year with costumes and decorations. One of the best moments of the night came when the unlikely pairing of Kristen Bell and Dave Grohl teamed up for a special performance.

Foo Fighters frontman Dave Grohl was hosting Jimmy Kimmel Live in the absence of its regular host, and welcomed actor Kristen Bell as one of his guests. He then asked if she wanted to perform with him, saying it would be "the biggest deal" to his children.

"If I was to jam a song with you, I would become the coolest dad in the world," he said.

The Frozen star then performed one of the Disney phenomenon's most famous songs: Do You Want To Build a Snowman.

As Bell sang, dressed as Tom Selleck's character from Magnum PI, Grohl joined on drums, dressed as talk show legend David Letterman.

Soon the whole studio band joined in, and the music grew heavier.

Before long, the song had evolved into Metallica's 1991 hit Enter Sandman, which Bell also sang, but with a deeper voice and... to be honest, a bit more strain.

Prior to the performance, Bell and Grohl discussed their costumes and Bell dressing up - at her daughter's request - as Frozen's Elsa, the sister of Ana, the character Bell played in the smash hit 2013 film.

You can watch the video of the performance below.