"Break off in case of sparkly vampires" - I think this would be even more effective without the "Sparkly" part. But In all seriousness this sign is racist against vampires. A hate sign is what this is!
Halloween Garage Door Decorations - Trace your hand a few times on black paper and then cut the hand shapes out. Tape them to the back of your window. Then add "Don't open dead inside" in huge letters on the garage doors.