VIDEO : Kristen Bell & Dave Grohl Perform Frozen & Metallica Mashup

Halloween gave fans a great deal this year, but you probably didn't expect it to produce a crazy rock version of Frozen. That's what happened last night however when Frozen's Kristen Bell stopped by Jimmy Kimmel Live. Bell was dressed up as Magnum P.I., and sitting in for Jimmy Kimmel was guest host Dave Grohl. The song starts off quite normal, with Bell reprising her role from Frozen. Bell will reprise her role as Anna in the upcoming Frozen 2, but for Halloween, she actually dressed up as Elsa.