They are going to eat your balls

Las Pollas del Metal (The Metal Dicks), a heavy metal band, are on tour to promote their first album. On the road to Galicia, their van suffers a flat tyre and they have to stay overnight at the "Gutierrez's town", a small village located nowhere. Next day, the town is throwing a festival where its inhabitants celebrate the patron saint's day. The Mayor invites the artists to join the celebration and they accept, without knowing a brutal danger awaits them.