That's what happened to motorists in Portland, Maine this week, and city officials say they are more angry than frightened. They're trying to find whoever tampered with an electronic sign.
The sign at a road construction site originally read "Night work 8 pm-6 am. Expect delays."
Wednesday morning a hacker changed it to read "Warning Zombies Ahead!"
City spokeswoman Nicole Clegg tells the Portland Press Herald that tampering with a safety device is a misdemeanor punishable by up to a year in jail and a $1,000 fine.
She says the sign is a safety precaution and changing it could have led to driver distraction. And she says it's not first time such tampering has happened involving a highway sign.