Just please learn from our mistake and don't do it after dark unless you like the idea of dozens of angry dogs chasing you all the way. (findingbeyond.com)
That's meant to let people inside know someone is entering, and also give the delivery person a chance to check for potential hazards like angry dogs. (theverge.com)
Eventually you find her house, a bland wall facing the street, guarded by a massive angry dog. (scientificamerican.com)