Thor and his bitchin' hair-metal band practice their rawk anthem in a deserted country house, where something... evil lurks, in this awesome scene from Rock 'N' Roll Nightmare. I love the cup-vomiting rubber penis monster.
Rock 'N' Roll Nightmare, from 1987, is just a cornucopia of rock awesomeness. It has some of the most ridiculous monster costumes and evil puppets of any movie, ever - including a great scene where a rubber-gloved hand bursts out of the drummer's chest and attacks a topless groupie. The movie's climax, where lead singer Thor turns out to have amazing powers of his own, is an instant YouTube classic, for reasons that should be obvious: