Dave Grohl confessed he was left "speechless" when horror legend John Carpenter agreed to make a cameo appearance in Foo Fighters slasher movie Studio 666.The Halloween director pops up for a brief appearance in the film, and also composed a theme song for the blood-soaked tale, in which the Foos portray versions of themselves.Grohl told Yahoo Entertainment UK that Carpenter's involvement was "entirely a coincidence" and came about because of a Kevin Bacon-esque trail of connections.Studio 666 will be released exclusively in cinemas on 25 February.