As a warning for would-be burglars/fools?
Or too cheesy?
I live in the mountains in the sticks. We don't need signs because it is assumed that there is one or more guns in almost every house. I worked arson claims for years and anytime I looked at a burned house and didn't find the remains of guns in the house, the odds were that it was burned by the owner. They always took their guns out of the house before they set it on fire.