It doesn’t get much more surreal than this – Dave Grohl, dressed as former Late Show host David Letterman, drumming furiously along whole the actress who played Anna in Disney’s Frozen sings ‘Snowman’ and ‘Enter Sandman.’

Yes, it’s a halloween thing.

Grohl’s choice of costume, as Letterman rocking the beardy retiree guise he’s made his own since his show was taken over by Stephen Colbert in late 2015, is startlingly convincing, down to the circular glasses and old-school varsity jacket.

Jimmy Kimmel, who has garnered considerable attention recently for his outspoken criticism of the Trump administration’s wayward healthcare policy, is taking a week off. Other guest hosts this week include Shaquille O’Neal, Jennifer Lawrence and Channing Tatum.

Kristen Bell, appearing on Monday night’s show to promote forthcoming festive flick Bad Mom’s Xmas, opted to dress up as Magnum PI-era Tom Selleck, complete with questionable 1980s perm and oversized moustache.

During the interview Grohl told Bell, world famous for her role as dorky princess Anna in massive Disney hit Frozen, that his three daughters Harper, Violet and Ophelia would think he was ‘the coolest dad’ if they could jam a song together.

Sure enough, Bell took the mic for a rendition of ‘Snowman’, her opening number from Frozen, familiar to millions of children and their longsuffering parents around the world.

After a couple of verses Grohl jumped on the house drum kit and the two launched into a spiky, growly version of Metallica’s ‘Enter Sandman’

Later in the same episode Grohl joined a straitjacketed Alice Cooper on stage to perform Cooper’s classics ‘The Ballad of Dwight Fry’ and ‘Killer, closing the night with a grisly onstage beheading of the shock rock icon. Except it turned out to be Grohl’s head. https://youtu.be/_XK6u1Evo6A?t=12m05s Well there’s something you don’t see every day.