Beware of Dog

Upon entering a little country store, the stranger noticed a sign warning, "Danger! Beware of dog!" posted on the glass door. Inside, he noticed a harmless old hound dog asleep on the floor beside the cash register.
"Is that the dog folks are supposed to beware of?" he asked the owner.
"Yep, that's him," came the reply.
The stranger couldn't help but be amused. "That certainly doesn't look like a dangerous dog to me. Why in the world would you post that sign?"
"Because," the owner explained, "Before I posted that sign, people kept tripping over him."