Watch A Costumed Dave Grohl & Kristen Bell Perform A Frozen x Metallica Mashup

Dave Grohl was the guest host of tonight's episode of Jimmy Kimmel Live, and because it's Halloween, he did the whole thing dressed in a shockingly realistic post-Late Show Dave Letterman costume. While interviewing guest Kristen Bell, who was dressed as Magnum, P.I., Grohl revealed that his daughters are big fans of Frozen, so naturally,…