Drivers and pedestrians on outbound Harrodsburg Road a half-mile outside Man O' War Blvd. saw a previously blank road sign come to life with a disturbing message: "Zombies Ahead."

Steve Barkley was walking his dog. "I didn't know what to think," he told ABC 36 News.

Doug Durbin was driving home with his son, Joseph. "It was a very bright day and very visible but I didn't know what it meant," he said. Joseph said, "I was looking at the side of the road and I asked him why -- zombies -- why would that be a sign of the road?"

But the mystery was beyond the reach of a father-son talk. The sign is rented by a construction company working on a sewer project southwest of Lexington that runs along Harrodsburg Road - and a risk management expert was unamused by the undead reference.

Mike Lyttle of Mack Construction and Excavation called it vandalism, an example of "sick humor," says the company will file a police report, and promises a root cause analysis. Which means they'll try to figure out how it happened and how to keep it from happening again.

Texas and other states have been plagued by sign-hacking zombie lovers. A few years back, a sign dealing with traffic on a UK football game was altered to display an unflattering reference to the Georgia Bulldogs.

However, had Sunday's sign prank been a warning of a real-life zombie apocalypse, it appears most would have been unprepared. Three people interviewed by ABC 36 said they gave no thought to the possibility of such a thing, while Gina Durbin said, "I really just thought that maybe it was some kind of activity at one of the churches or something up ahead."