"I'm Dave Grohl dressed as Dave Letterman sitting in for Jimmy Kimmel, it's confusing, I get it, especially if you're home watching right now stoned to the bone," the guest host said, donning a long white beard and a letterman jacket. Grohl wore the costume for the entirety of the episode.
Grohl's costume was an inspired choice as the Foo Fighters were recruited to perform on the series finale of The Late Show With David Letterman in 2015.
During Grohl's 10-minute opening monologue, the guest host poked fun at a North Carolina newscaster that dressed as "Dave Grohl" for Halloween – "That's like the opposite of a tribute band," he joked – and recruited parents for the annual viral hit "Hey Jimmy Kimmel, I Told My Kids I Ate All Their Halloween Candy."
Grohl also sat in with the audience to play Jimmy Kimmel Live's traditional Halloween game where the show mashes up two costumes and the audience needs to guess the "weird ass" character, like the Handmaid's Snail, Marge Gimp-son and a Vanna White Walker, with Wheel of Fortune's Vanna White making a surprise cameo to portray the Game of Thrones-inspired mash-up.
In what was perfect Halloween synergy, Alice Cooper was one of Grohl's guests, with the shock rocker – dressed as himself, plus blood splatter –sitting down for an interview with Grohl/Letterman where the two discussed haunted houses and the time Cooper met the real Colonel Sanders.
Grohl and his Foo Fighters then joined a straitjacketed Cooper on stage to perform the singer's Seventies hits "The Ballad of Dwight Fry" and "Killer" that ended with a morbid magic trick: In the medley's final minutes, Cooper loaded himself into a guillotine that "beheaded" the singer in front of the audience. However, when the head was revealed to the audience, it was a copy of Grohl's head and not Cooper's. Grohl smooched his severed head in the waning seconds of his guest-hosting gig.