Confused? Don't be!
Our good pal, Dave Grohl, dressed up as late night icon David Letterman to host "Jimmy Kimmel Live" on Halloween. That costume was ON POINT! Then again, we know Grohl knows how to have fun in costume (see: Learn To Fly and Run videos)
Actress Kristen Bell was one of the guests and Dave performed a Metallica/Frozen mashup that was tremendous!