A friend of mine is a deputy with the sheriff's department canine unit.
One evening, the deputy was dispatched to the scene of a possible burglary, where he discovered the back door of a building ajar. He let the dog out his patrol car and commanded it to enter and seek.
Jumping from the back seat, the dog headed for the building. After lunging through the doorway, the dog froze and backed out. My friend was puzzled until he investigated further.
Then he noticed the sign on the building: